What if some mode was added where there are a few ships on the board, each one capable of catching one color? You'd really have to work together to achieve a great score. Or some duel mono mode where the two ships can hit eachother, the one with the most captured colored blocks or less grays would win? What even if you just have to dodge grays and push the other player into them, maybe grabbing coloured blocks (of which there would be a lot less on the board) to reduce the count of grays captured?
I'm just throwing in some ideas.