I've already shilled for these two a lot but why not take one more opportunity:
Blasphemous II is about as good an indie Metroidvania as I've seen. An incredibly unique art direction, a good progression system, varied environmental design, lots of worthwhile things to discover, and absolutely fantastic combat with some of the best boss fights I've seen from the genre. The second to last boss fight still sticks out in my memory almost half a year after beating out. There's a few nitpicks I can make, like enemy variety and the frankly annoying requirements to get an ending that doesn't completely suck, but start to finish it's one of the best indie games on the market.
On the opposite end of the story spectrum, Pizza Tower tosses out the depressing atmosphere and is just an all around fun time. A bizarre Warioland spiritual successor that makes it work, mainly due to some incredibly fun controls, a great selection of variety with level design, and some surprisingly entertaining boss battles as well. It's absolute nonsense from beginning to end, but it's the good kind of nonsense, the kind that makes you want to come back and try for better and better ranks. Another game that would probably end up in my top 10 indie titles ever.
Some honorable mentions for other lesser played/indie titles that deserve recognition: Ghostrunner II, In Stars and Time, A Space for the Unbound.