Game rules of Overlap Attack (and gameplay)

About Overlap Attack, from BoardGameGeek:

It is a 2 players versus abstract strategy game. To win the game, any unit that can reach the opponent's Homebase. It's inspired by Chinese chess. Players have 8 units each, with 4 different tiers. Merge and respawn are the key elements of the game. To get the stronger tier units on the battlefield, players have to get two units in the same spot and merge them to upgrade the unit. Respawn is the privilege of the lowest-tier units. All defeated units will be returned to the supply area instead of being removed from the game. And players can always respawn the lowest-tier unit once per turn, if they haven't merged this turn, and the supply area has a remaining lowest-tier unit. Overlapping attack is the special weapon of the lowest units. If there is a cannon platform for the lowest unit, it will jump over the cannon platform and do a super long-range attack.