Fuse Blocks

Same numbers that touch fuse into the next power of two. Earn sparks from fusing 3+ matching tiles (2 sparks for 4+), plus a bonus the first time you make a new high tile (bigger tiles = more sparks). Clearing costs more for bigger tiles (2/4/8 = 1 spark; higher values cost more). Bigger board tiles unlock bigger drops with no upper limit. The drop pool grows toward 10 values (retire every 2nd unlock until 8, every 4th until 10). At 10, each new unlock retires the lowest, and higher drops become more common.