Alien Arena use its own engine CRX, which team COR Entertainment has used in previous

projects of similar subjects.
CRX Engine - is a modified hybrid of two engines - from Quake 2 and Quake 3, released in

2005 under the license GNU General Public License.
Supports a large number of effects, realistic shadows, dynamic lighting and more. The new

version of the game made a lot of changes: improved weapons effects, per-pixel lighting,

high-resolution textures, more careful use of resources, improved balance of weapons, a few

changed physics.