@kleeder Thanks for the feedback! To get the mechanics right, I had to pull a few Tod Howard's, which made the game run slower than I would've liked.
first, by default projectiles cannot collide into walls. To fix this I had to make invisible sprites for the projectile to collide with.
Second, every frame one of those walls checks if the right number of crates are in the right spot.
Third, to keep the crates from clipping into the player or into walls, I had to make sure that the crate was a certain distance away from the player in order to move. That led to the creation of the "strength push " mechanic.
All in all, I like the GB studio engine, but if I use it again, I'd probably modify the source code a bit to save myself some psychological torment.