One that I've been coming back to for years now is Solitairica (iOS, Android, Steam). Have you ever wished for a game and somebody just made it exactly like you wanted? I had been playing "golf-style" solitaire games like Fairy Solitaire for years. It's a really satisfying solitaire variant that's been re-skinned a bunch of times, but without a lot of innovation. Each version would offer a few "power-ups" to spice up gameplay, but I always wished someone would take it a step further, which this game does brilliantly. It adds a full-on RPG character progression over a series of solitaire "battles". It's a free-to-play game on mobile but you can unlock everything for a very reasonable price. If any of this sounds interesting to you I absolutely recommend it.