Multiplayer Online Battle Arena
An action-RPG sub-genre, very similar to two-way assault mode in FPS games.
Alternate names: Aeon of Strife-type game, Defense of the Ancients-type game
Name variations: DotA-like, AoS-like
The first video game about Multiplayer Online Battle Arena was released in 2003.
* Both sides have a Thing-They-Must-Defend (let's call it HQ from here on), destruction of that HQ signals victory for the other team.
* Levels consists of usually 3 main pathways to reach the opponent, these are usually called Lanes.
* The lanes are connected with each other via usually much smaller paths that have poorer visibility for various reasons.
* Each lane has about 3 defensive structures in succession that must be destroyed in order to be able to damage the HQ. Only one lane needs to be destroyed to damage the HQ.
* HQ spawns waves of AI controlled minions that fight alongside the players.
* Players control RPG-like characters selected before the game starts. These can't be swapped during single game.
* Players gain gold by killing enemies or destroying their structures, which they use to purchase equipment.
Games usually last from 25 to 45 minutes during which the player characters fully reach their level cap (somewhere near 20 usually).
* MOBA is a name coined by Riot games, has limited recognition (Riot and S2 mainly, the two companies running currently  most successful Dota-style games).
* Action-RTS is a name coined by Valve, and has gained some momentum because of marketing.
... however, the genre has little to do with RTS beyond originally being a mod for an RTS game. The genre is not so hard-set that it requires RTS-like top-down persective nor does it really have any elements of RTS games left in it. The game is actually much more comparable to 2-way siege/assault mode in FPS games.
Some strategy elements can be present, but this is usually from chosen character (minion controller) rather than the general design of the game.
Parent groupsAction-RPG, Action-Strategy, Multiplayer
|A||1998 - Aeon of Strife (AOS) StarCraft custom map released|
|B||2003 - Defense of the Ancients (DOTA) WarCraft 3 custom map released|
|C||2005 - Dota AllStars appears in esports tournaments|
|D||2008 - Gamasutra article on Dota|