I know one more idea and it is called END You draw about to pixels only and it has like 150 life and when the life ends it expodes! into a hot crazy magma and lava! EDIT: the pixels turn into THE END and it pops out magma and lava.
There is a 'vine_mode' that makes plant grow up wood. It's key is 't'. The multithreading is only for the new gravity (which nothing uses yet), there may be some other enhancements, but the multithreading is not the source of the speedup