Crimsonland

Crimsonland is a top-down action game. You maneuver around a featureless plain killing aliens, zombies and other nasty things as they wander onto or teleport into the screen. Your goal is to survive. To help you, powerups occasionally spawn from slain enemies: they either give you some kind of bonus (slow motion, freeze, and so on) or a new weapon (shotgun, plasma minigun, ion rifle, etc). As you kill monsters, gain XP, and level up, you are granted "perks" that may be beneficial, or may involve some kind of tradeoff for a benefit. "Long Distance Runner," for instance, lets you run faster if you keep moving. "Death Clock" makes you invincible, but you drop dead in 30 seconds.

There are four game modes, one of which is a secret end-game mode.

In Quest mode, you are required to kill a certain number of bad guys (and any that dynamically spawn from spawn points) who come at you in some kind of pattern. In one quest, you may have dopey aliens wandering around in squads. In another, you may fight plasma-breathing spiders while tiny little spiders harass you. In another, every monster might be invisible. Finishing a quest unlocks a perk or weapon.
In Survival mode, your only goal is to stay alive as long as possible, claiming the highest score possible. The difficulty of doing so increases substantially, until eventually even the common monsters are Made of Iron.
In Rush mode, you are given an assault rifle--that's it. Stay alive as long as you can. Infinite ammo, but even more monsters.
In the last mode, you kill monsters by typing words!

To give the game a little added longevity, it tracks high scores, both locally and on the internet.

Tropes used in Crimsonland include:

Abnormal Ammo: One powerup loads your gun with Fire Bullets. They HURT.
Alien Blood: Averted. Every creature has red blood. After all, it's right in the title of the game.
Awesome but Impractical: Many guns are powerful but have ridiculous reload times. There are perks to help with this. Good examples are the Plasma Shotgun and the Mean Minigun. The Minigun has the additional disadvantage of making you slower in a game where running is a primary means of survival.
- Special mention goes to the Splitter gun, which is available after beating every single level on Hardcore mode. When the bullet strikes a mook, the bullet splits in two, then those bullets can split again and again and again by striking additional mooks. The drawback is that the bullets from this Splitter can hurt your character, and with swarms of monsters in Survival mode, the game becomes a literal Bullet Hell. This gun is really useful, though, when picked mid-to-late-game, coupled with powerups and invincibility, it can take care even of those Made of Diamond mooks.
Awesome but Practical: The most generally useful guns, like the Ion Cannon, are also kinda badass.
Shoot From Hit Points: One perk turns your HP into ammo when you are reloading, so that you can keep firing at the cost of some HP. One other perk does this with your XP.
BFG: Anything with "cannon" in the name. The miniguns probably count, too, and some of the special shotguns are close.
Disc One Nuke: You could very well get Bonus Magnet, Bonus Economist, and Telekinesis as your first three perks. This makes most levels and early Survival relatively easy. In a different sense, once you've unlocked them there's always a chance your first weapon could be a BFG.
Emergency Energy Tank: The Bandage. Pick this perk and you regain full HP (contradicting its own description). Once.
Grim Reaper: The Reaper Got You...
Hyperspace Arsenal: You can carry at most two guns, and you need a perk to do that. There's nothing stopping you from taking two Cannons, though, and your character is never shown actually carrying the other one.
Joke Item: The Blowtorch. It's a flamethrower with a range about as long as your nose. It's actually fairly strong, but the range is so short that it's nearly impossible to use well.
Ludicrous Gibs: A low-key example, given that it's all just blood. Although the game does earn its name by the end of a round. Blood and enemy corpses do not disappear. Ever.
Meta Powerup: One of the perks gives you a wider selection of perks at levelup.
Mini Game: AlienZooKeeper.
Mook Maker: Those stationary spawner-things.
More Dakka: Fast-firing guns are a key to surviving. There are perks and powerups that do nothing but make your guns shoot faster.
Not Completely Useless: Even the Blowtorch has its uses. Try it on things that can't move.
Power-Up Letdown:
- Some perks are... we'll say "extremely situational." This mostly applies to ones that either put you in a near-death state, or change the conditions for dying--like Death Clock. Like most of the game's perks, though, they're Not Completely Useless.
- Running over a weapon that doesn't suit your perks can cause this. Between the ability to pick up stuff by pointing at it (yes, it's a perk) and the hordes of monsters, it's sometimes very easy to grab that Pistol by accident. There's a perk to keep this from happening, though.
- Freeze is like this sometimes, too. If you're trying to beat a level quickly, the last thing you want is bad guys frozen offscreen.
- There's a perk that lets you gamble a bit: 50% chance you get 10k XP, which is almost guaranteed to get you at least one (if not several) level up. What happens if you don't get that? You die.
- In survival, there are a few perks that are at least... a bit strange. There's the one where you die, but you get 18% more score. Or the one where you get a nuke that blows up when you die. You will get your revenge, I promise...
Power-Up Food: Here, eat this bandage.
Randomly Drops: Weapon drops are random, so you might spend a long time looking for your favorite weapon--and if you switch away from the pistol, the drop rate for weapons decreases. If your first monster drops an SMG or Assault Rifle, you're in for a long round.
Short-Range Shotgun: Actually, averted. All the shotguns do ridiculous damage up close, but only the sawed-off is useless at long range.
Smart Bomb: There's a perk that kills everything on the screen. It costs 2/3 of your health to take it, and it only works once. The disease from the "Plaguebearer" perk can act this way, too, if the screen is crowded.
- There's also the Nuke, a vicinity smart bomb powerup that explodes a considerable radius of Mooks when you touch it.
Sprint Shoes: The Speed powerup. Don't run out in the middle of a crowd. There is also the "Long Distance Runner" perk.
Standard Shooter Guns: You start with a pistol. Your first few weapons are shotguns, an SMG, an assault rifle, and a rocket launcher. The Cannons fill the "big gun" role. Guns like the ion minigun and gauss shotgun are a little more unique, and once you have everything unlocked there's no real weapon progression to speak of.
Unorthodox Reload: Aside from the abovementioned perks that let you shoot away your health and experience, there is a perk that let you reload faster by pounding the mouse button, and another that makes you reload faster if you stand still. There's even a perk that makes you hate reloading so much that plasma explodes out of your body whenever you have to reload.