It's one of the pulpiest science fiction premises out there: a scientist concocts a serum that allows him to shrink, but forgets to mix in anything that actually stops the shrinkage from happening. In Size Matters, the scientist is you, and you've got minutes to pull together a potion that will restore you to normal size - or you'll disappear completely.
Size Matters has been bubbling away in Early Access for about two years now, adjusting formulae and tuning equipment like the chemical processor, reverter, code combiner, and antidote producer. You can set all the starting conditions for each shrinky run: how tall you are when you start out, how long you have before you shrink down to nothing, how long your reagents take to process, and even your jump height.
The neatest thing about Size Matters, really, is watching the lab 'grow' around you in real time. It's a constant and visible process, so gaps you might have stepped over on your way to collect an ingredient could very well be a yawning chasm on the return trip.