Exactly this! The gameplay loop is solid and replaybale, and the gimmick allows for creative level design and emergent strategies. The only problem is that there is no real reward for getting more points (permanent upgrades, unlocking new content, etc.). You could argue it's an incremental game and the objective is getting as many points as possible, but it's a cheap approach to a proof of concept that - if expanded - could be a solid standalone game.