Superheroes is a block-placement puzzle in the 1010 tradition: you're given shapes to place on a grid, and you score by completing full rows or columns, which then clear.
The trap is that there's no rotation and no gravity — a shape has to fit exactly where you put it, so a board that looks open can suddenly have nowhere to place the piece you've been handed.
No — that's what makes it hard. Each shape has to fit exactly as given, so the board fills in ways you can't correct.
By completing full rows or columns, which then clear from the grid and free up space.
Yes — drag blocks onto the grid. Nothing to install.