Counter-strike: Source

1v1 AWP_India.  First to 10 kills wins.  Single elimination.

Starcraft 2

1v1 small map.  Round 1 and round 2 are best of 3. Finals are best of 5.  Single elimination.

Fall Guys: Ultimate Knockout

2 players join a game.  Play 2 full rounds together.  Add both your placements.  Higher number is eliminated.

Overwatch

1v1 practice map.   Both players play the same hero which is chosen at random.  First to 5 kills.  BO3 single elimination.

Dota 2

1v1 mid lane.  Both players play the same hero which is chosen at random.  First to 3 kills or first to kill tower.  BO3 single elimination.

COD: Warzone

Play duos with opponent.  Most kills in the match wins.  Regular game mode.  1 Gulag.  Gulag kill counts.  No buy backs.