[aardvark179]

Yeah, this one doesn't seem so hard. Variants like 144 are a challenge because you can fill the board with tiles that can never lead to your goal, and it's easy to get into a situation where you can't help generating them.

[mishop]

I thought I'd ask for a goal 3^6 (729). But this is impossible with this algorithm.

243 243 243 x x

81 81 81 x x

27 27 27 x x

9 9 9 x x

3 3 3 x x