Here is the full list of all 34 Offensive Combat: Redux achievements.
Finish 1 game fully
Buy your first avatar part from the store
Kill a total of 100 enemies
Kill a total of 1000 enemies
Kill a total of 10000 enemies
Die a total of 100 times
Die a total of 1000 times
Die a total of 10000 times
Play 10 games
Play 100 games
Play 1000 games
Complete 10 pwns
Complete 100 pwns
Complete 1000 pwns
Get pwned a total of 100 times
Finish a multipwn
Get 100 multipwns
Get a 100 kills with the chain gun
Get a total of 1000 Headshots
Get a total of 1000 Nutshots
In CTF mode, capture the flag a total of 100 times
Kill 100 bots
Kill 1000 bots
Kill 10000 bots
Play 10 bot matches
Play 100 bot matches
Buy your first weapon mod
Buy your first melee weapon
Survive an entire round without dying once
Get 10 kills in a single life
Kill 6 people within the combo timer
Complete 6 pwns in a single Game
Have a Kill/Death ratio of 2 or higher at the end of the round
Buy your first Grenade