ACR has a mutator to make gameplay similar to the original AC.

ACR supports v8 maps from AC.

Combining modes and mutators leads to many more possible game settings

More ways to enjoy the game

Damage fading over distance, bleeding, drowning

More server-sided code

Ignore neutral votes; veto admin votes after second press

showing explosions and shotlines

making it easy to see kills

unlike AC, no need to spam the spawn button

separate chat and main consoles, unlike in AC, where many kill messages can hide the chat.

Run an AC server to promote ACR.

Play AC to promote ACR.