The sequel allows for up to four players picking between four/five characters and sharing cash and towers, requiring careful management of resources; each player has a small arsenal to build, which requires careful management to overcome continual waves of enemies.
Towers themselves come in several varieties, including gatling guns, mortars, towers that slow the enemy down, and so forth.
The first game was released April 15, 2011, and followed by its sequel on May 15th, 2013. To date, four DLC packs have been released for the sequel, plus a skin pack for the core characters.
Sanctum and Sanctum 2 contain examples of:
Abnormal Ammo: Guns can fire anything from fire shells, electricity, nails, lazer bolts, sawblades, or even small flying drones.
Action Girl: Skye, the main character. Her sister Sweet joins the fray in the sequel, and TSYGAN is available as a DLC character.
All There in the Manual: It's possible to get a better grasp on character backgrounds and The Verse by reading dev diaries posted to social media and offical sites, as well as other promo materials such as the Elysian Archive. They explain the backgrounds of Skye and Sweet, explain Haigen joined to get out of the ghetto and get a job, and even reveal TSYGAN (despite zero in-game indication) is actually a hacker named Charlotte Wray.
Prior to her release, DLC character TSYGAN was revealed through her hacking the official Facebook page and controlling a twitter account. Additionally, eight codes found in the sequel can be entered into a real website for extra backstory. The comic it unlocks reveals that TSYGAN is planning a revolution against the rich oppressors, and Haigen is a slum rat tied to her; acting as a mole, he becomes a core guardian to feed her information and aid in overthrowing them.
The Elysian Archive, which, provided the player finds the codes hidden in maps, grants backstory and character background for the sequel. A list of unlock codes can be found here.
Art Evolution: The second game's official art is a lot more Western and cartoony than the first's, which was more animesque and occasionally had a semi-realistic depiction of Skye. Skye is a lot less pretty looking in the second game, with a scarred lip and most of her hair shorn short, exception of the hair spike at the top.
Attack Its Weak Point: Most of the enemies have glowing points that grant bonus damage or, in the case of heavy armor enemies, are the only vulnerable spot. Unless playing with certain loadouts and/or perks, hitting weak spots can be vital, as turrets never intentionally hit them.
Back-to-Back Badasses: Sanctum 2 allows for up to five unique characters across four players, who each have their own specialties and unique abilities.
Boom, Headshot: Most enemies have their weak points in their head. It's also the only way to make Tanks vulnerable, since that's where their weakpoint is, and Floaters and Bobbleheads are immune to damage anywhere else. Made even more important in the sequel as several new shielded "heavy" enemies can only be damaged by weakspot hits or attacks from powerful weapons or towers, and certain perks focus on enhancing weakspot attacks.
Bottomless Magazines: In a sense — whilst weapons require reloading, players carry an infinite amount of all ammo, meaning they need only worry about reload times and tower resources.
The "Friendship Turret". As their defining trait is that they increase in quality with number, filling the map with them and a slowdown turret can allow you to do significant harm very quickly.
The "Mind Control" and "Drone" turrets. With the former turning a specific enemy friendly for a period, and the latter creating armor-piercing drones, it's entirely possible to win rounds by letting them do most of the work.
The core perks and the "Phoenix" perk. The former allow bonuses like core counterattacks and minor core healing, and the latter allows you to instantly respawn (or normally respawn when they're deactivated) after dying; in other words, entirely passive and boring, but are capable of saving a game from loss.
Bottomless Pit: Near the edges of several stages. Hoverers are particularly dangerous in certain stages as their attack will send you flying very far.
Cold Sniper: Sanctum 2's SiMo - but that's to be expected since it's a robot and named after the highest kill-count sniper ever.
Damage-Sponge Boss: Soakers, which have ridiculously high HP but become larger and lose defense the more they are hit. Big Walkers are similar, possessing less overall health but are larger and don't lose defense.
Dance Party Ending: In the first game, Skye likes to shuffle or do the Caramelldansen after her victories. The same happens if the core is destroyed, only with Walkers in top hats dancing instead of Skye.
The Dev Team Thinks of Everything: The maps are pretty large, and extend to regions where you cannot build and enemies do not tread. Exploring said areas can result in finding spare mines, or even hidden easter egg, such as well hidden buttons that unlock doors to joke areas.
Double Jump: A possible perk, which even stacks to a triple jump if used with Skye.
Difficulty Spike: While Sanctum 2 game is manageable on the first two worlds, world 3, Giant Trees, features three difficult levels to solo: Train Station, Roadworks and Abandoned Lab.
Early-Bird Cameo: Sweet's official profile can be found in the original game and Haigen makes an appearance as an NPC.
Fragile Speedster: Runners, which come in large swarms and dash like mad, but are individually weak. They're also very small, making them harder to hit with anything but the machine gun. The Gliders, as noted above, are the airborne version.
Game Within a Game: Sanctum 2 features six playable arcade machines, usually well-hidden in their respective maps. Completing them all nets you an achievement.
Genki Girl: Sweet is just about the polar opposite of her sister personality-wise, being a lot more cheerful and enthusiastic. However, she shares Skye's enjoyment of seeing Lumes go boom.
Skye herself in Sanctum 1, who was hyper... about seeing Lumes die.
Glass Cannon: Bobble Heads. They are slow, but they will almost certainly hit you in a one-block wide path and are invulnerable except when shot in their weak point. They have very little health, though, so they tend to die quickly despite swaying their heads to make it more difficult.
Hell Is That Noise: The noise the core makes whenever an enemy pass through your defenses you thought were perfect will make you rush back at it really fast.
At level 4-4, The End, a very loud noise will be heard when bosses are about to appear.
Hold the Line: The only Game Over condition in the sequel is if the core loses all health; even if everyone dies under the no respawn "feat of strength", the game will continue until the core is destroyed or enemies are killed by the core.note A certain perk allows the core to counter attack for 2000dmg when it's hit, meaning it's possible to still win post-death.
In the Back: Floaters only take damage from headshots fired from behind. Joined by the massive Heavy Walkers in the sequel.
It's a Wonderful Failure: Lose, and your AI shouts "WHAT HAVE YOU DONE?!" as the core goes critical and explodes, and you get treated to a screen of Skye sulking while the lumes with top hats dally about.
Jack of All Stats: Walkers, which have average speed and defense, and come in decent-sized groups. The Spore Pods are the airborne version.
Blockers are nearly as fast as Chargers and can hit just as hard, but also have a lot more health and the ability to shield themselves at the cost of mobility.
Despite being one of the shortest core defenders, Haigen has an impressive 150% base health, and deals massive close range damage.
Luckily My Shield Will Protect Me: Floaters have a shield which nullifies all damage, their only vulnerable point being their heads when shot from behind. Tanks possess a shield that reduces damage but can be disabled by attacking their weak point. It regenerates if they aren't attacked continuously. Finally, Blockers curl into a ball when attacked by the player (but not when attacked by turrets), reducing damage done to them until the player lets up.
Marathon Level: The final non-DLC mission, The End, lasts for only one very long round. You have 50 tower bases, 6000 resources per player, random enemy types, and six bosses (two of each) to fend off.
The Tanks, which have a shield that reduces damage (potentially to nothing from weak attacks), but can be hit in their weak points For Massive Damage.
From Sanctum 2:
Armored Heavies which has a lot of armor and shuns nearly everything unless it hits their weakspot. Thankfully they are as slow as they are as well armored giving you most of times more than enough to deal with smaller threats and then focusing on them.
Infected Explorers, which can not only soak up tons of damage, but are Nigh Invulnerable. After "killing" them, they begin crawling and fully reheal; players have to kill them entirely again in a matter of seconds or they stand back up and heal again, forcing players to start entirely over.
Gatling Towers. Sanctum 2 adds new automatic weapons, like Skye's default Assault Rifle and the secondary Submachine gun that any character can equip.
Skye herself applies as, upon a second consecutive hit of the same enemy, she starts receiving +2% damage for each hit, with each bonus lasting up to 5 seconds. Naturally, by riddling a specific enemy with bullets, it's possible to boost right up to a +100% damage limit, allowing players to seriously harm well protected enemies.
Secondary Fire: Every weapon has two types of fire, which usually allows for alternative tactics. For example: Sweet's rocket launcher can lock on to one or more targets; Haigen's shotgun can load remaining shells into the barrel, allowing for higher damage multi-shots; and TSYGAN's Ballista can do lesser base damage, but inflicts shock damage to the surrounding area.
Self-Imposed Challenge: The sequel adds "Feats of Strength" which act like Halo's difficulty-modifying Skulls, adding attributes to the enemies like increased speed and aggressiveness (towards the core and you) along with more health and regenerative abilities, and worst of all the harsh penalty of disabling respawns until the next wave combined with decreased returns when recycling towers. There's a good reason to try these out, as each feat added gives you an extra 20% experience boost.
Silliness Switch: The victory/defeat screens in the first game are all of Skye/The monsters goofing about.
In the achievements, there are several. The "Legolaser aimed shots"'s icon uses a white-and-black filtered picture of Legolas from Lord of the Rings while "I am SUPER ANGRY" uses one of Leonidas from 300. There's a whole collection of them relating to The Protomen* If You Replace The Working Parts, You Get A Different Machine, We Will Build Heroes, and Hope Rides Alone, as well as one called Giant Enemy Crab.
There are references to I Love Strawberries, a failed game that the studio previously worked on.
In the sequel mission "Biolab", heading up to the left-hand doorway, turning left, and following the path reveals an Explorer hanging over a pit; when you approach, he shouts "Fly, you fools!" before dropping.
SIMO in the sequel is named after Simo Hayha, the sniper with the highest body count ever. Fittingly, he's a sniper.
Sociopathic Hero: According to the comic book sold with the retail version of the game, Skye was apparently noted to have sociopathic tendencies during training, and is referred to as such in the sequel. In-game, she's Laughing Mad, but this is otherwise an Informed Flaw. In Sanctum 2, in-between games, the comic strip cutscenes show her as lacking some empathy for the Conscripts, and being flippant toward a base commander who does not like Skye's track record.
Sudden Downer Ending: At the end of the core game, the team protects the final core in the lair of the Lumes, holding off everything that is thrown at them. Fleeing as the caverns collapse, the first thing the player sees is an enormous lume stomping towards a city, shrugging off cannon fire from the attacking city and vehicles.
In Sanctum 1, the achievement "I Said STOP!" requires the player to shoot an enemy in a slow field with a freeze grenade.
In Sanctum 2, Haigen's main shotgun applies, as the secondary fire causes spare shells to load, allowing him to empty his entire clip in a shot if desired. Combined with his close range damage boost, only giant and armored enemies can survive it, and even they will find a significant dent in their health.
Also in Sanctum 2 is TSYGAN's final shot bonus. Calculated as "25% of damage done x clip size", it can be the most harmful move in the game if used correctly. For example, her primary crossbow has a max damage of 2970, players can cause 7425dmg from one non-weakspot crossbow shot.
Too Fast to Stop: Chargers can run extremely fast in a straight line, but tend to bottleneck in tight corners because they can't turn well.
Urban Segregation: Despite the opening level being set in a shiny, high-tech city, the ARG explains there's rich areas behind higher security, and structurally-weak ghettos filled with the poor and the unemployed. In Haigen's story, he explains "Brightsiders" have the right to vote, own property, and work a real job; unless you're born there or have the right to work there, you don't get the same rights. In the comic book, they're also commonly bait and fodder for the lumes.
Video Game Demake: People who preordered Sanctum 2 got "Super Sanctum TD", a sprite-based 2D tower defense game.