Here's a list of the currently available game modes (Including the New ones) :
1 - Deathmatch : Free-For-All, Kill everyone and try to get most frags.
2 - Team Deathmatch : Similar to DM, But players are separated to 2 teams, the Team with most frags wins.
3 - Soul Harvest : Similar to TDM, But players need to Pickup souls of their victims quickly once killed, the opponent team can recover their friends souls to prevent the other team from getting them.
4 - Warpath : Teams gain points by controlling a moving sector, The Team with most points wins.
5 - Freezetag : Freeze the enemy team by draining their health, and thaw your allies, the first team to freeze all opponents wins.
6 - Clan Arena : Similar to TDM, Except players have only one life and have to wait for the next round if killed.
7 - Domination : Teams have to extract 3 sectors to score rounds, the Team with most wins is the winner
8 - Exodus : Capture the moving flag and return it to your team base.
9 - Sector : Similar to Domination except there's no rounds limit, Instead there's time or points limit.
10 - Bloodrush : Similar to Deathmatch, except you have to kill to gain energy to respawn, Getting killed drains the energy, the fewer remaining players, the higher energy drain rate.
11 - Possession : Few players are randomly chosen as Possessed to play as low-hp Prawlers and Infect all the Humans Before time runs out.
12 - Infernal Run : Similar to Exodus, players need to throw a ball at their enemy team goal, The player who has the ball cannot use guns, However can Instantly glory kill enemies with a single melee hit.
13 - Co-op : via SnapMap, up to 4 players team up and fight together.
14 - Misc : via SnapMap, Custom game modes, each has different objectives and setup.