Versatility and weapons in FPS games

When picking up a new FPS and jumping into the campaign, you're usually handed a generic weapon and thrown against the enemy. I've been playing a lot of shooters in my life and it wouldn't surprise me if 90% or more of all the enemy kills in single player games have come from either 1: a machine gun or 2: a shotgun.

My biggest issue with versatility is not that you're almost always using a weapon similar to the ones used in other games, it's that they make you revert to using the same playing style. I've mostly been using the same strategies against NPC enemies since Doom and it usually goes like this: peek out with your machine gun, kill an enemy or two then hide behind a corner. Use a shotgun or similar to kill the stupid enemies that come charging towards you. This is not interesting gameplay, it's abusing bad AI.

In cases where the AI won't mindlessly charge you as soon as they've "seen" you, you might have to be a bit more clever but the basic weapons will still suit you extremely well. They are just so versatile.

Versatility depends on several different factors but these are the ones I think most important: accuracy, clip size and reload time. A weapon with decent-to-good accuracy and large clip size, like the machine gun, gives you a big margin of error in short encounters. It also makes it possible to conserve ammunition, using only the necessary number of shots to take out low HP enemies instead of using overkill weapons. In most games you will have enough ammo to use the first weapon throughout the game and with a high damage upgrade like the grenade launcher in Half-life it will work against bosses and several enemies at once.

Later on in a FPS you will usually receive more powerful weapons that are meant to work in one situation and that situation only, like a sniper rifle or rocket launcher. Since there generally is no way to use them cost-efficiently I tend to save them for boss-fights and cases where I don't feel my first weapon is strong enough. Once I've run an encounter that's meant to be beat with one specific weapon I tend to hang on to specific types of ammo for the rest of the game, effectively turning the weapon into a key for a challenge. If there is no more similar challenge, I will have carried around a weapon for the most part of a game and never used it.

Instead of giving the player one or two weapons to use the entire game, I'd like the other way around: you start with a weapon that limits you to a specific type of gameplay and as you progress you will receive upgrades that let you tackle all kinds of challenges. Then at the end you can find a super weapon that works for all situations but has a limited supply of ammo (will probably be unbalanced for multiplayer). Depending on the size of your enemies, the size of the area where you're fighting, your own cover vs. the enemies' cover, range etc. there are enough ways to create different types of encounters that making the weapons reliant on different situations should be no problem.

Less versatile weapons will not create excellent games by themselves though. One of the major problems is enemy AI. As long as hiding with a shotgun in a corner will make the enemies run up to you, people will keep hiding. In games like Gears of War where you're even supposed to hide behind walls and anything that runs up to you will just get chainsawed to death. While giving players too versatile might make a game stale, making the enemies more versatile will make it less predictable. The first time I had a grenade thrown at me in Half-life I was shocked that just hiding behind something didn't work. I needed a more advanced strategy. The new one was hiding and running away if I heard "grenade" but still.

By giving a specific enemy type two separate attacks and then mixing enemy types you will get very complex patterns of attacks with only three or four different enemies. If a player has to keep track of what weapon to use to take out the most dangerous enemy in that group composition, enemy encounters will become more difficult.

Limiting the player, forcing them to be creative and clever in coming up with their own strategies and adapt to situations creates good gameplay. Having a simple solution for every situation doesn't.