Ablockalypse now has a block editor which allows you to modify the shapes of the blocks.
For additional details please see the the following steam guide, or youtube video below. View game page
This update also includes some minor bug fixes.
Ensure blocks are regenerated when exiting and starting the game.
Ensure the y axis is correct for blocks put into play regardless of shape or size so that the bottom of the block lines up with the top of the board.