gamedesigngraphically:

It’s very easy to design an exponentially growing power curve. For instance, player A has six tanks, player B has four. Each tank takes two hits to destroy. Each fire on the other. Player A now has four tanks, Player B has one. The next round, Player A will annihilate Player B without further losses.

This sort of effect can make even small differences hard to come back from. One easy solution is to cap growth (bottom right). Another might be diminishing gains, but those have to be balanced with player’s getting frustrated.