First-Person Shooters are, well, games about shooting people. From the first-person point of view. You're seeing through the eyes of a killer, and no, they're not all psychos, and yes, sometimes it's more than justified. You think those zombies are gonna kill themselves? People play FPS games mainly to blow off steam, or because the game play is really fun. It's a visceral experience that can be gummed up by adding too much of the wrong detail. Specifically: Don't let the story get in the way of the gameplay. As Yahtzee says in his review of Ninja Gaiden 2 (not an FPS, but...):
Necessary TropesWell, you're probably going to need some sort of Death Tropes involved. While it's possible to make an FPS without killing anything, it rather defeats the point of the genre. If you have examples to the contrary, please post them down at the bottom of this page under Extra Credit. One-Man Army: While multiplayer mode is usually the better option, any solo missions come down to One-Man Army. So far, the Artificial Intelligence behind NPC allies is, well, not exactly living up to its name. You could, of course, change all that... down in the Subversions category.
Choices, ChoicesFPS works well in a variety of genres and settings, from The Wild West to modern warfare to futuristic Sci-Fi. You could probably make a caveman one where you throw rocks at things. So figure out what sort of feel you want. Awesome guns are vital to the genre, and the most powerful possibilities come from Sci Fi and Fantasy. Even if you wanted to do a Wild West shooter, you could borrow elements from Functional Magic or Steam Punk (see Deadlands). Still, modern weaponry is getting pretty powerful, and it's not like firing off a bazooka makes you feel underpowered, so don't discount the possibilities. But, basically, your genre and setting are simply the background for the use of cool guns against various enemies. Health Bars: Dying from a single bullet = not fun. Realistic damage = not easy to program. Invisible health bars = just one more thing for Yahtzee to complain about. But they're still choices. Consider health powerups, as well as the possibility of conserving hit points as a strategy (not getting hit too much early on in a level). Try to make the game fair yet tough. Refuge in Audacity: Many modern shooters try to be serious, but really, just because the Media Watchdogs will call it a Murder Simulator doesn't mean that you can't have fun with it, mostly. You've got three basic routes here: standard military combat, sneaky spy missions, and over-the-top superspy / supersoldier empowerment. Because sometimes it's fun to cut loose and not worry about the casualties. Pacing: How much a player has to stay in cover or keep on moving.
PitfallsWatch the AI! One of the easiest ways to make players complain about your game is to have horrible AI, be it in allies or enemies. The two biggest offenders in AI are reactions (how they act when, say, someone is shooting at them), and interactions with the player character (running out into your line of fire = a bad thing unless it's an old-school-type shooter). If you're going to include non-invincible friendlies, make sure you put some time and effort into making them intelligent. You're going to be walking on a cliff, with the chasm of "irritates the player" on the one side and "upstages the player" on the other. It may be best to leave them out altogether. Hint: If the player is ever standing to the side as the NPC's interact without him, you've got a big, big problem. Definitely be wary of segments that change the way the game is played. Mainly, we're talking about Vehicle-driving sections. All too often, not enough attention is paid to making sure these control as well as the on-foot action. Players don't appreciate chores, and sloppy and unresponsive driving are certainly considered chores. Press X to Not Die and cover-based shooting are boring. if a character is encased in six inches of superdense metal, he shouldn't die from two or three shots. Unless they're delivered to the face.
Potential SubversionsFirst of all, why would you want to subvert these tropes in the first place, you ask? After all, they do often work. And, in and of themselves, Tropes Are Not Bad. However, a well-done subversion will call attention to your game, and people who look at your game will, understandably, be far more willing to buy it. Again with the AI: Have the enemies react in a realistic manner to bodies lying around, to gunfire, etc. And give all the enemies a reason to be where they are. They're not standing there so you can shoot them. They're standing there to guard the door, or deliver crates to the inventory supply clerk, or to take out the command post, whatever. They have a life apart from their connection to you, the player. Take it seriously: But run with it, have the players character really be an superhuman psychopath who slaughters hundreds of people. (Hey, it worked for Halo.) Of course, if you paint the player as the villain, you're unlikely to be very popular, so find a constructive use for your superhuman psycho. Don't include the old standbys: Wait, this isn't a subversion, this is an aversion. Unless you call attention to it (e.g., with finding the standard guns but not using them, or having a gun look standard but act strangely). Anyway. The standard guns are ingrained into the genre; this gives you a golden chance to ignore them and try for unique and gimmicky weaponry. But remember to make them good: People complain about bad gimmicks but almost always praise good gimmicks. For a good example, look at Half-Life 2's gravity gun. Might be hard to do but if you get people to think in weird ways and jump through your silly hoops to use an arsenal of awesome gimmick guns it would be totally worth it. Alternatively, just pump the player character with Plasmids or have them become the host of a demon that likes the shade and have him or her shoot lightning or impale enemies without having to resorting to any type of gun! Just listen to Yahtzee, in his review of Painkiller:
Suggested Themes and Aesops...First-Person Shooters have Aesops? More seriously: FPS's can have plots, though often the best plot is an Excuse Plot: A plot that is basically there to explain why you're shooting at these guys, and little else. War plots are very appropriate, though possibly overused. It may be difficult to get the player to sympathize with the main character, more so if the main character is a faceless, nameless psychopath. And even if your main character is not a psychopath, the player may play him like one anyway. Be aware that anti-violence Aesops will probably come pre-broken (and given that the point of the game is to have fun via killing things, it'll be combined with a You Bastard as well). There's always the chance for an Aesop about appropriate violence. After all, with zombies, robots, StarfishAliens, genetically engineered monstrosities, crazed wild predators, and so forth, you can easily be shooting everything in sight without a hint of Values Dissonance. But what about innocent bystanders, or allies who have fulfilled their role in the game?
Potential MotifsKilling... things? More seriously, the main "motif" is going to be the genre/setting. It limits (in a good way) which kinds of guns and enemies you can include. You should also put some thought into whether your characters can get bloody, muddy, dirty, scraped up, etc. It'll affect the whole feel of your game.
Set Designer / Location ScoutIf you choose to go with an existing war, you're going to have to do some research, but then again, it'll be pretty easy to work out the look and feel of the scenery. Then again again, everybody's already done that. On the other hand, if you choose to delve into a timeframe or location not already well represented in the market, you'll have the chance for a whole new look and feel, but you'll have to come up with a lot of stuff on your own. Or you can follow God Hand's path and make the background dull, ugly and minimalist. No one will care if the game is filled with sufficient Awesome.
Props DepartmentAh, the guns. There are, of course, the old standbys, but always consider ways to mix things up. You should put as much loving care into the design of the guns as you would a main character in any other game. Because let's be honest, in a First Person Shooter, especially one with a faceless protagonist, the guns are the real stars. Other than guns (or weapons in general), there are secondary items to consider such as medikits, jet packs and such. These things should of course be useful (i.e., help you kill stuff), but they don't directly kill stuff, so there isn't a huge list of possibilities... but there are a good number of cool things you can do with items. These are of course completely optional, but expected by now. You should also consider how many weapons and items the character can carry at once. Many games severely limit the inventory; while this adds a level of strategy, the more stuff the player can have at a time (and that you give him), the more options available to him, and the faster he can lay out the enemies. Depending on sub-genre, the speed at which the player can mow down enemies may be a very big factor in the amount of fun he has. Also, most of the shooters of the past decade have used a two gun limit, with maybe a pistol as a third (Halo, Call of Duty, FEAR, etc...). It could be fun to allow players to carry around a whole arsenal for a change, assuming you are willing to part with a bit of realism. Another idea is to inject a little more realism, even to the standard weapons. Many weapons tend to follow certain tropes that aren't entirely accurate to how the weapon acts or is used in real life. You can inject some new life into the weapon(s)
Costume DesignerMilitary outfits make everyone look the same, but may make it easier to tell who to shoot and who to spare (unless people start ignoring the Geneva Convention and putting on the wrong clothes and all). However, colorful and interesting enemies are.... more interesting. Consider each enemy type as its own character and design it as such, with an interesting look that compliments its attacks and purpose.
Casting DirectorUm... guys who like to shoot things. Guys who like to blow things up. No, seriously, unless you're going to go with an AFGNCAAP, then you'll need to have a character who's at least willing to kill people he's never met, even if under duress. And that's still a wide range of characterizations. Alternately, you can not have a person willing to kill people he's never met. At least at first. Explore what happens to a person forced to do so anyway, and maybe even give the player a chance to not kill anyone. Also, you can always make a female hero. How many FPS's have those? (No One Lives Forever, Mirror's Edge, Perfect Dark, Metroid Prime, and Clive Barker's Jericho (technically)) Enemy-wise, you can have Nazis, aliens, zombies, lots of stuff. And since most enemies are going to be onscreen for all of three seconds, they should be distinct, colorful, and interesting.
Stunt DepartmentBesides people dying and Stuff Blowing Up, consider the game effect of falling from a high location, and whether or not characters recover their health over time if they get a breather.
The Epic FailsStudy the ones people mock or complain about in order to see what not to do. And these include...