Nob Studio says:

All player starts with a War Machine, and some power ups card. The objective of this game is to defeat all 15 cities' War Machines. The basic battle concept is actually a rock - scissors - paper game. Your machine can exist in 4 modes, 3 modes where 1 is always better than the other, and the last mode which pwns all. When you win each turn, your machine will push your opponent further back and whoever pushes their opponent of the edge wins the battle. To make the game much more exciting, we have include power up cards which will modify your attack/defense. Earn money through battles and buy these cards. I recommend playing the tutorial before trying the game.