Most Harvest Moon games tend to have at least two or three bugs each — though this has become rarer since Harvest Moon: Tree of Tranquility. These are usually among the annoying kind, but a few fit in this category. Among them:
The original's Day/Night system: Time seems to pass normally in an accelerated cycle, except for one thing - night will never end until you go to bed. This means that you can clear your entire property, till and plant seeds on every available square, and water each and every one of them...in one night. The only downside is that some tasks can't be done after a certain time of day (most importantly, the shipping bin resets in the morning, so anything you throw in after the shipper won't count until then) - but for everything else you've got all the time in the world!
HM 1's Love glitch: The game's eligible brides will like you more when you talk to them every day, but talking to them more than once in a day won't do anything... in theory. Actually, if you walk out of her house, then back in, it counts as a new day. Pretty much mandatory for getting the best ending, which requires you to have a wife and a kid... within three years.
HM 64's Horse Betting glitch: If you place your bets with the Mayor's wife, then exit instead of confirming, the bets will go through, but the money won't be taken out of your wallet, allowing you to bet on the horse race for free.
HM 64's Dog Glitch: You can raise Karen's Heart Level by continuously showing her your dog. This is because the "one affection point per day" check never triggers for just this one affection boost, meaning you can max out her affection rating on day one with enough effort.
Harvest Moon 3 has the shipping glitch. Let's say you have 97 potatoes and 1 Wild Berry. You want to ship more, and just in general get more Wild Berries. You go and select the potatoes and the Farmers Union guy you're talking to will ask how many you want to ship. You press down on the D-pad which shows 97 potatoes. Press the B button and go to the Wild Berries. When it asks how many you want to ship, press down again. Now you get to ship 96 Wild Berries! Ship those and check your storage. Chances are, you have a higher number of Wild Berries now. The glitch itself messes up at times when you want to get more things, such as giving you a lower number of Wild Berries after shipping 99 items, but it is definitely useful. There seems to be at least no way to get 0 Wild Berries if you ship it like this. And it works for every shippable item!
HM DS's 1 Billion Gold glitch: Hiring the Fishing Sprites during Winter, then shipping junk items (items that ship for 1G each) during a day when they're working for you will set your money level to 1 Billion. There's a chance doing this will invoke a Game-Breaking Bug that will corrupt your save file, make this option a Death or Glory Bug.
Harvest Moon: Friends of Mineral Town: When stumbling upon an outdoor Rival Heart Scene, the clock will not restart until you leave that particular area. Stumbling upon such a scene with your fishing pole and basket in tow is an excellent opportunity to load up on lucrative fish and other items. Also, you don't lose stamina during Festivals, so you can power up your tools to full experience (except for the watering can, which can't be used while empty). Both glitches were removed in More Friends.
Harvest Moon: Back to Nature: On your first day on the farm, where Mayor Thomas will take you on a tour of town, before exiting your house, you can keep swinging your tools (except for the watering can) to gain full experience levels, since the game will lock your stamina level at 1 so you can go through with the required cut scene. Works with any day where you'll experience a cutscene as soon as you open the door, but this is the first one and most easily predicted.
Harvest Moon Another Wonderful Life: The infamous 99 Items glitch. If you take your controller out of the #1 port and plug it into the #3 port, then press the Z button a few times...you get 99 of every item. Simply switch back to the #1 port to resume play.
Harvest Moon DS lets you keep on getting friendship points by showing your pet to someone, with no limit. It is a great way to get early access to Leia the Mermaid.
Harvest Moon: Magical Melody has a bug which randomly grants you infinite money. It isn't known how this happens, though, and it may lock you out of the note for being poor as you can't lose money anymore.
More of a developer oversight than a true glitch but prior to Patch 1.06, Abigail would appreciatively ask "How did you know I was hungry?" when you gave her an item she liked. This included gemstones. Abigail's unusual tastes quickly became subject to Memetic Mutation and eventually became an Ascended Meme.
If the player is married to Maru, then occasionally she will wear her nurse outfit to bed and say "Shhh! Don't let the doctor see you!" when you try to talk to her. Less sexy is how sometimes when you marry Shane, he'll bring his chicken to bed with him.
It was once possible to plant fruit trees everywhere in the game, including in some interesting places, such as the bathhouse. This got fixed with the 1.1 update, but the same update reverted the previous fix for planting fruit trees inside the greenhouse and outside the dedicated soil area, making it an example of an Ascended Glitch.
Due to the way the game handles giving the player items, it's possible to name things with item numbers, including your farmer, causing the items to spawn in the player's inventory every time the name gets mentioned. In this way, it's possible to get very rare items like the Iridium Sprinkler, Ancient Fruit, Prismatic Shard, etc. every time someone says the player's name. Find an NPC who says the player's name every time you talk to them, and you'll never have to worry about money ever again, breaking the game's difficulty in half.
In a similar vein, the pale green wallpaper somehow shares an item ID code with the Prismatic Shard, the rarest and most valuable gem in the game. So you can instantly befriend everyone except Haley (who hates Prismatic Shards), summon/forge the Galaxy Sword, and Baleful Polymorph away unwanted children... with a piece of wallpaper.
Krobus' shop has, as well as its usual itinerary, one item that can only be purchased once per day. However, closing the shop window and then opening it again will allow you to purchase the items again without having to wait.
SimCity 2000 has a bug involving the use of a joke cheat code. In the first SimCity game, typing "FUND" gives you some money, but Sim City 2000 instead offers you a loan at 25% interest (very, very bad idea). However, the game also dynamically adjusts what interest rate you get on regular loans by examining your current loans. Get a few of these joke loans, and the dynamic interest overflows and goes negative. A loan with negative interest? It means you get paid every year for having debts!
Also, the SNES version of the game has a bug involving a careful use of a pause button and allowing the tax screen to drop below zero, which instantly pushes it to the maximum value (then capped at $999999). An easy way to beat any scenario.
Likewise, holding the pause button at the beginning of the Boston scenario allows you to demolish the nuclear reactors before they go critical.
The Sims 2 has a great bug where the aspiration reward that temporarily boosts toddlers' intelligence gets "stuck" once in a while and leaves the player with a supersmart kid that learns skills at triple the speed. It was fixed in a later expansion pack... then broken and fixed and broken... Depending on your expansion pack setup, it either is rare/fixed, happens fairly often, or happens every time you use the item.
There was also the potty-training glitch, where if you cancelled the action at the right time, the toddler would be instantly potty trained. That was fixed at some point too.
You can also, with moveobjects activated, move a Sim somewhere, rotate the camera, and then start making (non-intelligent and temporary) clones of that Sim. Sometimes called the Door-Clone Glitch, since it was named after misusing the door feature in Build Mode. The same cloning process can be instigated by shift-clicking a Sim somewhere when in Buy Mode.
The nannies are quite glitchy in The Sims, doing shit like lighting the house on fire, feeding babies that are full, ignoring the babies, sticking around the house indefinitely, etc.
Shown in MadameWario's Let's Play of the game, if your toddler sees you cheating on your significant other, their relationship status with you will drop with other family members of the house (any family member will get pissed at you for cheating). This means you can attack your toddler and fight with them. Sadly, the fight-cloud animation doesn't work when fighting with a toddler (your sim will just be standing there), but the small dialogue window does show up in the corner saying your sim is "not to be trifled with".
You can make a floating house, and do it without console commands. Place a bunch of pillars down, and then build your house on top of them. You can then delete the pillars, and the house will remain standing. You've wasted a floor of your house, but you can always use that space for one giant swimming pool.
The Sims Medieval had a minor but fairly helpful one just after the release of the expansion. One quest makes you create a food item called Boiled Goo, but if your kingdom wasn't involved in the War a Sim could actually make it any time without the ingredient from the quest. Since it gives a small positive buff, it could be an alternative to eating Gruel, which gives a negative one. This has been fixed; Boiled Goo can now only be made in the quest.
The Norn genomes in the release version of Creatures 2 have a flaw in their simulated neurochemistry, so that when a Norn walks into a wall, instead of getting the signal to turn round and walk away, they often continue to walk into the same wall over and over. This habit became known as 'Wallbonking' and is considered a classic Norn trait among the fandom, even though a fixed genome and later games (mostly) eradicated the behaviour.
This is far from the only problem in the Creatures 2 genome — the Artificial Stupidity is so rampant, it was dubbed "One Hour Stupidity Syndrome." While many programmers released fixes for this which targeted various aspects of the genome, the original genome is still quite funny in a schadenfreude kind of way. After one hour, the bugged genome ensures that your Norn will become incredibly stupid, to the point of total paralysis.
The "flying lemon" bug in the first Creatures is fondly remembered by fans. Other flying objects too, like the coconut crab COB.
A glitch in Spore lets you abuse how the game sets the limits for creature widths to make asymmetrical creatures, with different hands or limbs on each side. Eventually this was made easier by making it a legitimate game feature.
Also, limbs (but not hands or feet) turn invisible if the starting joint isn't connected to the torso. Somebody made a whole range of Rayman-based creatures this way! This glitch is also very commonly used to make creatures that perpetually hover above the ground (using invisible legs).
Monster Rancher Advance 2 has a Good Bad Bug... that unfortunately comes with a side-order of Laser-Guided Karma. Essentially: At the start of the week, before doing anything else, save your game. Turn it off and on again quickly. If done correctly, your monster will lose Fatigue and Stress points, meaning that, if done repeatedly, they will never tire. The universe's retribution for cheating to train your monster? If done repeatedly, this trick will kill the saving on your actual game due to its origins as a memory-clearing glitch.
Animal Crossing: City Folk has an oversight in the programming which makes it possible for the player to completely bypass the "normal" methods for getting nearly anything. When you go to someone else's town via wifi and then leave, as you disconnect and Copper wishes you a good day, the player can press the Home button to reset the game. Wifi normally does not let the player use the Home button at all. This allows for cloning items, including money. By having the host save the game, the guest can drop the item in the host's town and then use the oversight to reset the game BEFORE you return to your town, meaning the save when you return will not happen. When you start the game back up, you will have the item in your inventory, and your host will have a copy of that same item. Thus, it's possible for two people teaming up to get as many of a given item as they wish or as much money as they wish, and in this way completely bypass the normal methods of earning money or certain items. This glitch reappears in New Leaf (and works nearly identically, to boot; it's actually even easier to exploit since all you have to do is flip the 3DS' wireless switch while leaving).
NASCAR Racing 2003 Season: Unrealistic car setups work well with the original retail version on the faster tracks, to the point that the cars handle more like Indy cars and are somewhere between stock cars and Indy cars in terms of speed.
The original Transport Tycoon keeps cash on hand as a 32-bit signed integer, limiting your money to +/- 2.1 billion GBP (all other currencies are multiples of this base amount; USD = GBP x 2, JPY = GBP * 100 etc). It's possible to build a tunnel extending from one end of the map to the other, which makes the cost overflow. Shift-click to get a cost estimate, keep searching until you see something with a cost in the negatives, then build. Instant jackpot of 2.1 billion pounds. Did I mention this can be done shortly after the game starts? This was fixed in Transport Tycoon Deluxe.
In a similar vein, cash-on-hand can also overflow, suddenly shifting from 2 billion on hand to 2 billion in debt. The AI companies are not smart enough to begin wasting money once it approaches this number.
X-Tension featured an odd AI glitch: if you flew behind an enemy fighter and maintained a close enough distance - below 200 metres - they'd cease all maneuvering and just fly straight, forever. This made most fights cakewalks - aggro an enemy, park yourself on their tail, shoot until desired results achieved.
In X3: Terran Conflict, the ATF Skirnir missile frigate is a Game-Breaker even by the standards of its own class due to an extra zero in the damage values for its anti-capital weapon, the Shadow missile. As a result, it puts out 755 megajoules of damage per warhead on an eight-warhead missile. In an unmodded game, the toughest ship has only 12 gigajoules of shielding. Do the math. Egosoft never bothered to fix this in Terran Conflict since you have to board and capture the Skirnir to use it, but what with the full-scale Argon-Terran war in the expansion pack Albion Prelude, the bug was fixed so that Argon players wouldn't get their heads blown off the second a Skirnir showed up.
In ARMA II, an amusing bug can cause tanks (and presumably other armoured vehicles) to fly. By going to the Armory and selecting Utes as the map, the player should be dropped near an airfield. Driving over the boulders just south of the airstrip's centre will cause the game to freak out and launch your vehicle into the air at high speed. As an added bonus, your choice of tank will be completely unharmed when it lands turret-first at 200 kilometres an hour!
Goat Simulator carries this as a selling point. Seriously, it's listed under the Key Features on the Steam Store page: "MILLIONS OF BUGS! We're only eliminating the crash-bugs, everything else is hilarious and we're keeping it." Note that it's still entirely possible to crash the game via glitches: this earns you an achievement.
In Theme Park by Bullfrog, if your workers are on strike and picketing outside your park, you can break the strike by simply picking them up and moving them back inside.
In earlier versions of Command: Modern Air and Naval Operations, it was actually possible for a helicopter door gunner to sink a submarine. This has since been patched out of later versions, however.
Usually, you don't want bugs on a game like World of Tanks. The potential for player abuse is high, and the amount of complaints it would get is often even higher. However, one glitch that persists due to being seemingly impossible to predict or cause on purpose is caused by the server and client desynchronizing, with the client 'catching up' to the server and sometimes having ridiculous results, such as a tank teleports 20 meters to one side without warning, or suddenly spinning violently in place like a top, or doing high-speed reverse donuts. The kicker is that the game remembers these are multi-ton vehicles moving at what are now very high speeds, and it treats them accordingly. It's resulted in some rather amusing, one-of-a-kind situations, such as this incident where a tank destroyer is destroyed after it is suddenly roundhouse-kicked by a lagging tank.
In From the Depths's Neter Campaign early days, there was no classification for vehicle movement type (land/sea/air), only its max altitude and max speed. This could lead to jet aircraft being chased across mountain ranges by battleships on the strategic map, whereupon the start of the battle the ships would spawn several hundred meters in the air and plummet to their doom. Later updates allowed vehicle classification systems so boats won't attempt to cross land and vice versa for tanks, but the class isn't always properly set.
The Tug-of-War glitch from Cultist Simulator, as showed off in this tweet announcing its demise. Essentially, if you had only one card of a given type, and two things tried to pull it in (for example, both Inspector Wakefield and one of your reputation-destroying minions competing over a reputation card), instead of one definitively winning, the card would bounce between boxes until one ran out of time.