3.5 years of silence is a pretty strong indication that things aren't going well. If they are working on a major project, then as another poster pointed out, it is very likely stuck in development hell.

I already answered to you on that, "we dont know how big their game is, this year is already very strong for Switch lineup, Nintendo could easily saving Retros game for next year even if its almost done, Nintendo even basically said that Mario Odyssey could be dont for Switch launch but they decided to be holiday season because Zelda BotW alone is very strong game, Nintendo could easily save Retros game for E3 2018. like biggest new announcement". People also thought that Metroid is dead, that Nintendo doesn't work on Pokemon for Switch and that Pikmin 4 is dead, but Ninteno prove them they are wrong, people really need to be more patient, Switch is just 3-4 monts on market not two years, offcourse Nintendo did not anancued everything they have in development and that they saving lots a anancument for later.

Switch only being out for 3-4 months has nothing to do with it, Retro has been MIA for 3.5 years and still has nothing to show for it.

Of course it has, Retros is working on Switch game/s and of course that Nintendo did not show everything they had in development for Switch just 3-4 months after launch, even everything they have for Switch for next year. You cant know what Retros has to show, only Nintendo knows that, Nintendo can easily like plenty times now show and release Retros game in same year.

How long Switch has been out doesn't matter, hasn't stopped tons of other games being announced. 3.5 years of nothing is pretty much never a sign of a healthy development. If they are working on something big, there's a good chance development has run into problems.

Of course it has, buy time console will have more announcements than at start. I dont see that Nintendo announced tons of games, most of this years Nintendo Switch games are announced in January Switch event, and at E3 they announced just few 2018. games. If Retros game is holiday 2018. game than it's not unusual why we still didn't see it, in that case it's very possible that will Nintendo biggest E3 2018. announcement.

A late 2018 release would mean a 5 year production cycle. Retro have never even gone 4 years without releasing a game before now, and they don't even have the "first HD game" excuse this time. This long a haitus is not indicative of a healthy and productive studio.

It's entirely possible they're making a new IP, or a game that uses new technology, or that moving their game from Wii U to Switch has caused development problems. There is evidence that whatever Retro started work on in early 2014 changed direction or was even scrapped in the first 18 months of development. Kensuke Tanabe worked with Retro on every major game of theirs from Prime 2 onwards (so Echoes, Corruption, Trilogy, DKC: Returns, DKC: Tropical Freeze), but has spent the last few years working with Next Level on Federation Force, and now (presumably) Metroid Prime 4, among other things (Paper Mario: Color Splash, for example).

In February 2014, around the launch of Tropical Freeze, both Tanabe and Michael Kelbaugh (Retro Studios) confirmed development had begun on a new title. By August 2015, however, after the reveal of Next Level's Federation Force, Tanabe commented he had no idea what Retro Studios were currently working on. So clearly, within that 18 month period, Tanabe stopped working with Retro Studios and whatever project Retro were making was either scrapped, or changed direction.

A lot of people here are assuming that whatever Retro started work in in early 2014 is whatever they might be working on. There's some evidence that suggests that's not the case, given Tanabe's seeming departure from working with the company. It's also a very simple truth that games development is lengthy, complicated and prone to delays. I would assume Retro still have their own title in development, but that it has encountered delays, or perhaps it's even the case an early build or early project was scrapped entirely.

I don't see Retro making a Prime Trilogy HD. Nintendo could outsource that to Tantalus, or Monster Games, for example. More likely the former than the latter. Nintendo have a lot of patience when working with their studios, and I think they'll still be backing Retro to finish whatever game they've been developing. Looking into Xenoblade Chronicles' development history demonstrates the extent to which Nintendo will support projects coming from talented developers, allowing significant delays in order to get the game right. It's likely Retro now have a new producer from Nintendo's internal structure working with them, and that they're making their first major game without Tanabe's input since the original Prime, which Miyamoto produced.

Hard at work makeing the best 2,5D platformer Nintendo has? ei. a new DK game?

Again, we dont know how big their game is, especially if it's big new strong IP. This year is already very strong for Switch lineup, Nintendo could easily saving Retros game for next year even if its done buy now, Nintendo even basically said that Mario Odyssey could be dont for Switch launch but they decided to be holiday season because Zelda BotW alone is very strong game. Also, Retros could easily work on more games than one from end of 2013. until now.