Slay The Spire, I've accumulated over 2000 hours over 3 different platforms since it launched, I've 100%ed it and I've even played some of the mods (which I never ever do for any game) and I never get sick of it, whenever I have an hour and can't be bothered with doing something new I play a run.
I hope viewership end up being way higher on the weekend, LCS is a great product right now and it's such a shame that it has less people watching it than ever before.