The achievements (viewable after the jump) detail what sounds to be some sort of collection of various new and old Geometry Wars game modes including Geometry Wars: Waves which was included in PGR4. We say this only because the game's Phobia and Surf achievements mention Waves in their descriptions, but other achievements mention different game modes including "King" and "Deadline". We guess the most obvious proof that Geo Wars 2 will feature a compilation of new modes is the ever straight forward Unlock All Modes achievement.
We're pumped! We're excited! Bring on another round of Geometry Wars and another 200 Gamerscore! W00t!
[Thanks, Dynamo Matt]