Thanks! I played a lot with my friends on a 4x4 board and I never encountered a situation when no one could win. I know it's possible, but it seems like it's quite rare
Edit: I was thinking of adding something similar to 50 move rule in chess to counter it
By defensive, I mean always trying to block the opponent from winning - by attacking opponent pieces every turn. Each placement we can remove up to 4 "hp", but only add 1-2 "hp". So if both sides focus on removing opponent pieces, we will easily end up with stalemate due to having only 1 piece on board.
Another balancing idea is that we can give +1 hp to all pieces, and have all the attacks evaluated at once after player 2's move. This way player 2 gets more freedom to move "right next" to player 1, and do kamikaze attacks when needed.