The Trine series is a fantastic set of puzzle-platformers where each character has completely different strengths/weaknesses, all used properly to progress. Some compare them to the legendary Blizzard SNES title "The Lost Vikings" for this reason. A great feature is that the games allow for both solo play (with the player swapping between the various avatars) to online/local co-op , with each player controlling a character simultaneously!
The general player consensus seems to be that the first (Trine: Enhanced Edition - a free upgrade that added new graphics and otherwise improved the game) and second (Trine 2 : The Complete Story - A version with the latest patch plus all DLC/expansion content ) are given near universal acclaim in their genre however the third entry (Trine 3: The Artifacts of Power) had some issues with bugs at launch and made some gameplay mechanics changes that, while not being a bad game by far, labeled it not living up to its predecessors. This and the long delay put the future of the series in jeopardy, but it seems that with Trine 4 they're heading back to the 2.5D roots of the series ( T3 went for full 3D - worthwhile envelope pushing but many feel it didn't quite work out) and expanding gameplay dynamics in other ways such as for the first time 4-player co-op. I wonder if this will mean 4 characters? They haven't shown the 4th character, but I can't imagine how else this could work without forcing one player to have a non/minimal interaction "ghost" or something and that doesn't seem a good idea.
One great thing about the Trine series has been its Mac and most importantly Linux clients. It was one of the games that backed Linux in the "old" days when support was less likely so greatly appreciated. Given that all Trine games to date have offered Linux support, I was very hopeful that the 4th would continue the tradition but sadly it appears that is not the case. https://steamcommunity.com/app/690640/discussions/0/1842440600617693589/ - Frozenbyte has been making some unfortunate choices with titles like Nine Parchments to make them based on proprietary methodology and generally building the game without cross-platform gaming in mind. Now, things seem to have gotten even worse as a publisher is now in the mix and they've apparently "lost" a lot of the code and people who worked on previous Linux games. While I commend them for being forthcoming about it at least, it is frustrating to see this change of direction. Very disappointing indeed, especially in an era where more titles than ever are getting Linux support