The player starts the game with the hero Cathrine, who is on a quest to retake her homeland of Erathia.  In the story Adventure Mode, the player moves their hero through the world from node to node. Nodes can be caves, castles, monsters, or any number of things, but a battle nearly always awaits.  There are two main types of battles: open field battles and sieges, though their combat and strategic elements are similar . At times, there may be items, units, or buildings on the map that the player can click on or collect.

The players army consists of one Hero and a number of battle units.  The Hero has a set of unique passives and spells that are useful in combat.  Many heroes can be collected and enhanced, but only 1 can participate in the battle at a time.  Battle units come in 5 different types: Attack, Defense, Charge, Ranged, and Caster. Each class has its own general strengths and weaknesses, and each specific unit has its own equipment, skills, bonuses, and star level.  The number of units a player can take into battle is determined by the player level.

Before battle, units are placed strategically on a 4×4 grid.  Each type of unit has restrictions on where it can be placed. In PvE, opposing force placement can be seen, but not in PvP.  Once battle begins, the units move toward the enemy and attack per their described AI. Players only control when/where to cast hero spells, though this can also be put on auto-mode.  Hero spells cost mana, which is gained steadily as time passes. 

M&M Heroes: EoC has a large variety of game modes, including damage aggregation, AI controlled PvP, unit shard/enhancement farming,  training, and others. One mode that is particularly interesting, is the Guild Adventure Mode, where you are and your guildmates asynchronously explore a world map populated by enemy NPCs, resources, dungeons, production nodes, etc, and are contested by other guilds.

See a gameplay video clip here: