It's nice and cute but... The challenge is not very satisfying. Buying items is necessary as the enemies become quickly stronger, so you have to explore, to collect coins, but sometimes you just can't avoid being trapped. The enemies are smart and wait for you while they are close and on the same square color. That way they become a constraint on up to two directions on four total. Some more constraints, which easily happens, and you have to lose a heart. So with bad luck you lose heart over time, while spending time exploring is necessary. At the end I feel like I have to try repeatedly until some good luck let me go further than usual...
...but controling the two rats needs a constant focus which costs energy and becomes more tiring than challenging over a long time :/