Adrenaline is a freeware, top-down, multiplayer shooter. So basically, instead of seeing a first person view, you kinda see a bird's eye view. You can play with other players, and even the cpu!
Here is a list of some of the features:
Fast paced, high action multiplayer gameplay
Four game modes -
Death Match (DM), Team Death Match (TDM), Capture The Flag (CTF) and Conquest (CON)
Dozens of official, and hundreds of user-created maps
Many weapons to choose from (Assault Rifle, Minigun, Sniper Rifle...)
Multiple ammo types (Incendiary, Armor Piercing, High-Cal...)
Grenades, mines and knives
Tactical Nukes
Teleporters
Online stats tracking and global leader boards
Player achievements
Single player bots
Download: http://playadrenaline.com/downloads
Join the #adr room to come and play!
There currently aren't many servers being hosted, but hopefully someone here could have one up every now and then? Anyways, hope to see you on the battlefield!