I bought this game when I first made Steam account nearly ten years ago. There wasn't that many cheap co-op online game at that time, so my friend and I bought this to play co-op. It felt "indie quality" at that time for the genre. Movement, shooting, animation, gameplay system all are unpolished. Even right before I write this review, I played this and it's still the same quality-wise. But for very cheap price of below 1.00 USD when I bought this (and no other games to play at the time), It was fun while it lasted. The main mode is survival mode where you defend your base from dino invasion with wave-based loop. Every few wave, you have chance to upgrade your character, buy wepon/equipment. I don't know how many wave until you "beat" this mode because it's quite hard for low-level character/class. There are many other mode such as capture the flag, team duel, team elimination, conquest, and many others PvP modes.
Nowadays, there's so many good quality online co-op games, even from indie studio and can be found at the front of Steam page (of course through "Steam algorithm"). it's better to play those that have better gameplay, polished, and rewarding.