Fun take on the theme. Building up the level around the player as they play is a nice idea. If you continue post jam one thing that you can do is limiting the amount of information the level builder can see in terms of moves (to maybe just 2 moves ahead) and make the player a bit faster (or increase in speed over time). Then if you allow blocks to be played on each other or some other objects to be placed down to interact with the level it can really capture the panic making levels as a player wanders around vibes. Currently if youre going for ending on the flag you need to plan out the whole level ahead of time and then wait for the player to make their way over after awhile or get lucky and be able to place down the flag without having it blocked off by something else you did