After two years of development, a beta version of Steel Storm has hit the tubes, offering a taste of this free (and open source!) top-down shooter. It's a multiplayer game with both deathmatch and co-op modes, so might be worth a gander:
Steel Storm is an old school top down arcade shooter with score oriented competitive gameplay, and is designed for people who like fast paced action and have limited amounts of time to play computer games.
The events take place in an alternative universe where you control an advanced hovertank, packed with the most advanced and sophisticated weapons. Your task is simple, but, nevertheless, is not trivial. In the fight with presumed extraterrestrial invaders, you must prevail!