Teeworlds - FREE! - Extremely fast paced, cute, and brutal 2d shooter. Movement is grappling-hook based and really fun. To try and imagine how fun the movement is, think Quake 3 if it was 2d. It has people playing so if you want to try it out you can before it is selected for a playdate.
I suggest getting Alien Swarm from steam. It is free and controller enabled
I've heard it's heaps of fun.
Other than that my favourite free game at the moment is TeeWorlds and Red Eclipse (www.redeclipse.net)
Have fun dude! In the future when you have the cash SERIOUSLY considering getting some of the Valve games such as Portal, Half Life 1/2, Team Fortress 2 etc.
Teeworlds has been under iterative development for about five years now. While the lion share of development was done over a few months, keeping an iterative cycle has yielded some significant progress in non-critical areas such as UI, game types, localization and so on.
Some conclusions, then:
Hedgewars is like worms and teeworlds is a fun 2D shooter. These are good when you just want to have some quick entertainment.
Strategy: Frozen Synapse
Teeworlds: It's basically a 2d version of tribes. I am literally hooked on this game. The core game is a 2d platformer/shooter with wasd movement and double-jump, and different weapons scattered across the map. What makes the game amazing is a grappling hook. Whenever you press rmb (no cooldown), the character shoots a grappling hook and tries to reel it in.
This mechanic (combine with grenade jumping) changes everything. You can accelerate 10x faster than normal, go across the entire map (ctf5) in under 5 seconds, and hook onto other players to bring them into range of your guns or throw off their aim. All of these combine to create a game with an insanely high skill ceiling, but one still easy to get into and watch.
It's extremely fast-paced, and somewhat reminiscent of arena shooters such as quake in its mechanics- emphasis is on twitch combat, as well as controlling/defending powerup/health/armor spawns. The game is also open-source and very moddable, with lots of game types, though most people play CTF. Check it out, weighs less than 100mb and runs on anything.
Teeworlds. Have you ever read/watched a spiderman comic book/movie and thought, "I so want to do that!" ? Well, this game is like that too. Except you have guns.
The downside is that it's not much to look at - A lot of the appeal for me is that it runs very smoothly on my ancient netbook and takes up less than a megabyte of space.
I'll also vote for Team Fortress 2 (Free)
It's terrible. I'm sad to see it compared to Soldat but that's fine. I'm mortified to see it mentioned in the same thread as Abuse.
Crash Commando is a pretty awesome Soldat clone, but only for PS3.
What about Teeworlds? (I'm about to give it a try.) Aren't there any mods out there that are inspired by Abuse?
My kingdom for multiplayer Capsized. Oh well.
For my 2d shooters I much prefer Teeworlds, the cutest, most intense murderfest you'll ever play. I'm willing to check out soldat though, especially if it becomes an official playdate. Right now it looks like the only one I'll be able to join in on this week is Source Forts, but I'm really excited for that.