Congratulations, I'm happy to hear that you managed to escape

That particular objective is a bug which I intend to fix with an update.
The game used to have more walls when that was made and I forgot to change it when I reduced the number of wall obstacles.

Currently that particular objective is unobtainable because you'll never encounter 20 walls in one run, so you can either skip it or wait for an update, sorry.

The rest of the difficult objectives can be obtained (tested ).