Casual is one of the two core online gameplay modes. It's a mode in which you can enjoy playing with friends who are quite a few ranks away from you in Competitive, but with no worries about any rank, due to the mode not being focused on that.
There are five Casual playlists:
Note: Each player shares progression between all playlists in Casual (i.e. Shares the same hidden Casual MMR)
Standard is generally the most popular Casual playlist. As the name indicates, it is the standard online game mode. In standard, the team is composed of three players, therefore, teamwork is crucial to victory. Because of the number of players involved in the gameplay, it is recommended that players maintain tactical positions and rotation across the arena.
Doubles is a popular Casual playlist. Doubles is very popular because standard tends to balance the game less proportionally when there are more players to play with or against. In doubles, you need to co-operate with only one teammate.
Duel previously known as Solo Duel is arguably the most balanced in terms of raw skill. Because it is simply a one-on-one game, solo duel is not based at all on co-operating in a team, but on strategy and skill in the arena.
Chaos is a Casual playlist for bigger party, you can bring a team of 4 to the game of 4v4 on standard arenas.
LTM also known as Limited Time Mode is a Casual playlist that appear from time to time featuring new Arena's, mix of known modes, new modes and more! Limited Time Mode is a Limited Time Casual playlist that you can solo que or play together with your friends.
Retired Casual Playlists
Rocket Labs was a mode similar to Standard, but with a twist to the Maps and it was removed in Patch v1.53. The arenas from the mode started returning with Free To Play Season 2 as Limited Time Mode, and also included some new arenas into it's pull. 
|Competitive||Standard • Doubles • Solo Duel • Solo Standard|
|Extra Modes||Rumble • Dropshot • Hoops • Snow Day|
|Recurring LTMs||Spike Rush • Beach Ball • Heatseeker • Rocket Labs • Tactical Rumble • Dropshot Rumble • Boomer Ball • Winter Breakaway • Super Cube • Speed Demon • Spring Loaded|
|Event-Exclusive LTMs||Ghost Hunt • Gridiron • Gotham City Rumble|
|Mutators||Moonball • Demolition • Time Warp • Pinball • Cubic|
|Other||Training • Tournaments|
|Currently playable game modes appear in blue (including those that can be played in private matches).|
Permanently discontinued game modes appear in gray and are no longer available to play.