Biotech’s first big additions come in the form of children and reproduction, with colonists and outsiders able to get pregnant and give birth - either naturally or via technological means. Once babies grow into children, they can learn through lessons, play, or by watching adults work, with players able to determine their traits and passions every few years. Children given more attention and better education are more likely to become happy and talented adult colonists - but players can alternatively skip the nuturing and use growth vats to pump out soldiers and cheap workers to exploit. Alongside babies, RimWorld’s Biotech expansion introduces the mechanitor, a colonist with a special brain implant capable of psychically controlling semi-living machines. These mechanoids - which never get sick, or cold, or suffer mental breaks like humans - are grown in gestator tanks and can specialise in either labour or combat. The former can assist with everyday tasks such as farming, manufacturing, and repairs, while the latter can wield the likes of melee claws and blades, sniper weapons, and flamethrowers to aid in battle. The cost of all this robotic assistance, though, is pollution, which can poison colonists and pets, produce choking smog, even cause insects to swam the planet’s surface. There are, however, ways to mitigate its effects, such as freezing, export, and adaptation. Finally, Biotech adds gene modding, giving players the tools to create genetically-modified xenohumans with exotic traits. These can range from the subtle - a change in eye colour or personality - to considerably more dramatic attributes such as massive size, rapid regeneration, fire breath, and even immortality. These genes can be purchased from traders, acquired as quest rewards, or extracted from xenohuman prisoners, before being implanted, even recombined for strange and unusual results. RimWorld developer Tynan Sylvester has shared some thoughts on the design goals of Biotech’s new additions in a blog post on Steam. It also details some of the features arriving as part of RimWorld’s free 1.4 update, launching alongside the Biotech expansion later this month. 1.4’s key new features include the following: painting and colour customisation for walls, floors, furniture, and lights; functional shelves; two new turret types; starting possessions for colonists depending on their backstory; rot stink from corpses and meat that can develop into lung rot; more prisoners; a new heat overlay; a new mod manager and various other UI upgrades. RimWorld’s 1.4 update is currently available via the game’s unstable branch for those keen to check out its additions early, and more details can be found in the 1.4 changelog.
