Sorry!
Either way, you can pretty much get the gist of this game from the offset.

Run around a bunch of Alien Breed style arena shooting a bunch of aliens.
Each arena has it's own online scoreboard, and there's even a few Achievement-style icons to motivate you on each level.
Default controls are WASD and Mouse, but you can tweak these to play with all kinds of different control schemes.
The left sidebar shows your multiplier. Pick up the star tokens to upgrade the multiplier, but if the guage hits 0, the multiplier resets to 1.
The right sidebar is your weapon-upgrader. Kill a baddy to pump it up. Stop killing, and it drops back down again.
As it stands, it's a decent mix of graphics and gameplay, and the online scores should keep you playing for a while.
The current release is 0.95, and I'm probably going to be doing a final 1.0 in a few days, with any bug fixes, or what have you.
You can Download Alien Deathmatch, here or here. It's about 3Mb, and contains 20-odd arenas.