He adores Minecraft, though only plays at a basic level so this sounds perfect. Thanks mate!I would weigh in and recommend Minecraft Dungeons. Essentially Diablo lite with the Minecraft aesthetic. Have been having a blast with our 3 and 5 yr old.
Simple game play, build choices are defined by gear and quite flexible. Drop in/drop out co-op with mob quantity scaling accordingly.
Despite the simplicity, it does touch on key systems and concepts from more complex titles. Kite bosses, burn the adds, don't stand in the fire. Prioritise mobs based on type (caster>ranged>melee). CC is king. Utilise choke points. Stack bonuses and synergies wherever possible.
Don't expect great depth but it's clearly designed for a younger audience and does so admirably.