You wanna know about Warframe? Settle down and let me tell you a story
Note: I've not tried the switch version yet, however it's warframe, I've spent a *lot* of time on the PC version, and the switch version isn't that different.
Warframe is, for the most part, multiplayer. There are the main quests, most of which are singleplayer only due to how they are but are still 100% worth playing because they're made incredibly well and the story is great. There are options to be able to play on a private instance when going into missions, or friends only (I would presume this is still a thing in the switch version), or to be matched up with randoms.
Is it also 100% free. The only things that you HAVE to pay for (at least in the PC version) is community made cosmetics. The premium currency has a pretty good trading economy behind it. Once you get playing enough, and start farming what is called Relics, you can learn how to be apart of the trading and get the premium currency just through playing, no need to pay at all. I have over 250 hours in the game on PC and haven't paid a single penny, I've got friends who had thousands of hours in the game and none of them has paid either.
Imo, the game is really fun and worth sinking time into. Digital Extremes (The company behind it) absolutely love the community. The game came out in 2013, and their biggest update to date only came out this month, and there's a ton more to come. Everything to do with the game has had a ton of time and effort gone into it, and the story is interesting to follow. For a free game, it's seriously worth it.
Their stance on microtransactions, they hate it when you pay to play. There's a breeding pets mechanic in the game, and that used to be pay to use, however after a short time too many people were buying a lot of it and they thought it was wrong, so they removed the microtransactions and made it free. A lot of people buy the premium currency when huge updates like fortuna came out just because people feel it's not right we keep getting all of this completely free.