A document released this week by the EU Education, Audiovisual and Culture Executive Agency (EACEA), confirming projects it plans to help fund in 2018, has revealed that a number of indie studios are working on new games. The list includes many unfamiliar studios, but there are a few names that pop out: Bloober Team (Layers of Fear, Observer) is working on a game titled "H2O", Zoink! (Fe, Stick It To The Man) has an upcoming title called "Roll Them Bones", and Tequila Works (Rime, The Sexy Brutale) has something called "Lumberjack". Much of the list may well be made up of working titles, but one entry in particular stand outs as it's an unexpected sequel which has not yet been announced.
Trine 3, a fantasy adventure game, suffered somewhat at release because its switch to 3D resulted in a shorter game length and a cliffhanger ending which fans were largely not happy about. Many had feared this would be the end of the series, but this document seems to reassuringly point to another Trine game being in the works. Yes, Frozenbyte is apparently working on Trine 4.
While the full list is no longer available on the EACEA website, you can still check out a copy hosted by GameReactor who first spotted the publicly available list. While many of the other games are not confirmed final titles, it's still worth a peruse if you're curious if your favourite indie team might have something in the works.