A rare gem for PC gamers: an oldschool top-down 2D bullet hell shooter designed for co-operative play.
Features solid, challenging and non-stop action with 4 different ships to choose from, each with their own style of attack. Difficulty is highly scalable with 4 initial skill levels and 1 crazy unlockable one for the hardcore crowd.
The main campaign is pretty short, but different skill levels, modes and bonus challenge levels add plenty of replay value.
As of July 2011 the multiplayer is limited to local matches on a single computer. The developers have mentioned the possibility of adding online multiplay, so netgamers should probably wait and see how that turns out before buying.
Overall I'd recommend it for anyone who fancies intense co-operative action and can arrange gaming parties at their place.
Gameplay-wise it features a unique blend of using high maneuverability as your main asset against massive armies of demons, while exploring non-linear and non-scripted levels with plenty of secrets to discover.
To top it off, you get an unforgettable cast of hellish monsters, a legendary soundtrack, great multiplayer and possibly the biggest amount of free user-made add-ons for any game ever.
Overall, this game offers you more bang for a buck than any other action game does. I recommend running it via a modern source port though, the DOS executable included with the Steam release is archaic and definitely not recommended if you want to experience Doom at its best. So get ZDoom or another modern port and go kick some demon butt right now!