Heroes Inc 6: Overmind’s Invasion is an expansion to Heroes Inc 1, 2, and 3. All three games are required to use this expansion. In this expansion, an alien villain named Overmind is invading the Earth and only two heroes (Firefly and Liberty Lass) are there to fight him. Overmind is an alien with a very large brain and over-sized head. The scenarios in this expansion are linked together and are meant to be played in a specific order. For example, if the heroes lose scenario one, they move on to scenario two. If the heroes win, they can skip to scenario three.
The game uses a points system to buy characters with. Players have 40 points to spend on their heroes and villains in order to build the best group. The game follows the core rules of the other Steel and Glory games but adds new rules to accommodate for super hero fighting techniques.
Each turn, players activate a character which can take up to two actions, including fight, move, rest, climb, or stand/go prone. Characters can attack enemies that are one square away for melee attack or may use ranged attack for enemies further away. Fighting is based on power of the weapon, power of the character's attack strength, and power of the enemies defense strike. The hit points are calculated via 2D6 - the power of the attack. For example, if an attack had a total strength of 6 and a 10 was rolled, the attack would have a power of 4. The villain side has certain objectives (such as do a certain amount of damage to the city and exit the board) and the heroes win if they prevent these objectives from happening.