TMNT Guide to the Universe (1987) is, I think, the point where TMNT and Other Strangeness starts to get weird. By which I mean, starts to get sucked into the Palladium Books vortex of constantly increasing scales of conflict. You can start to see the shape of Rifts here, even though it was still three years off when the Guide game out.

The book, whose title I think is a conscious reference to Douglas Adams’ Hitchhiker’s Guide to the Galaxy, introduces space travel, space combat, some very Riftsy robots and aliens to the TMNT system. A lot of space is dedicated to two alien races, the Triceratons, a space faring race of humanoid warrior tricerotops who have popped up now and then in TMNT media, and the Ultroms, squishy, mostly friendly brain creatures who would eventually count Krang (decidedly unfriendly) among their number.