Okay, so the challenge in the bottom right corner is to place something that fulfills the rules of the 1 and 2 blocks - the ? block is important because it blocks you off from the obvious thing you would try
the O can't be placed there because it breaks the 1 block rule
but you can place the L so that it fills 2 of the 2-block and 1 of the 1-block
> Mines must be grouped into tetromino shapes. Two of each tetromino is used. Rotation and reflection are allowed. Tetrominoes may not touch orthogonally (on a side). They may touch diagonally.
from there i filled in that grey square because the cube can't touch, and then i knew the T had to be the top one and the S had to be the left one. so i filled those in. and that's where i currently am.
in a different way: the 3 next to the 2 was also key because it told me: a) if that bottom piece is an S, it can't poke out left, so it must poke down and b) if that bottom piece is a T, it can't make sense with the 5
therefore it's a down-poking S
i'm guessing this was not the intended way to find those pieces but i hope it's still valid logic?