Update time!
This update brings a whole bunch of changes, I'm not going to even remember them all. But let's get an overview:
Koopas can now manufacture monsters in the Mystic Hatchery. To make it work, you'll need to produce a 'potion of life' at the Magikoopa Sanctum, which, when drunk, will cause a Koopa to produce a 'monster egg corpse'. This must be deposited next to the Mystic Hatchery and can then be used to spawn one of many different monsters, ranging from Shellcreepers to Podoboos (careful with that last one!) The spawning reaction is free, though the potion itself will drain a magic gem to produce. Be warned, spawned creatures may be hostile at first, so be sure to deposit the egg inside a room surrounded by cage traps before running the spawning reaction. (Creatures can be spawned through walls.)
Koopas can also create a 'shell workshop' that lets them improve their shells in various ways.
As for Shyguys, they now can make a slot machine which allows them to gamble shining coins for subspace potions or various other items (mostly just regular plants though.) The more coins you deposit at once, the better the chance of getting a potion. Subspace potions are required to produce a subspace portal, which should last about a season. Subspace furniture is no longer seizure-inducing colors, but is instead a simple white. It will still fade away over time, but as long as they exist you can set them up to improve the value of your fortress and the mood of your shyguys. Or you can look for blocks, which will produce distinctive magenta-colored mushroom blocks that will let you construct large structures easily. Basically shyguys are more normal to play as now, you can't rely on subspace to produce everything but it'll be useful when it does show up.
Some other changes:
Cavern layers each have a new, distinctive look - SMB2-3-style green grass for the top, classic blue for the middle, and dark purple for the bottom.
Various creature behavior has been improved. Monty moles leave dirt behind when they burrow, geckos no longer kill each other before you even see them, Arachnes will show up, ? blocks will appear. Also some new creatures have been added. Watch out for food-stealing buzzbee swarms!
Ztars have been added. Every time you put a broken power star back together, it has the potential of producing a ztar as well. Ztars are heavy, useless, and actually have a negative value (exactly the opposite of a single Power Star), so they'll lower the value of your fortress unless you can get rid of them. Atomsmashers should help.