Witch & Hero is a great arcade styled romp perfect for short play sessions on the go. With a very addictive gameplay loop and a fun "protect the tower" objective, this game is a great hidden gem among a sea of indie darlings.
It's biggest downside is it's sharp difficulty curve which requires a lot of grinding to progress. The final (and only) boss is both infuriatingly annoying to defeat and a clever way in adapting the standard gameplay into a boss encounter with an unorthodox method in beating it.

Not much more than what it is, Tiny Dangerous Dungeons is a bite-sized metroidvania for mobile devices. For those looking such an experience on mobile, this game provides a good scratch of that itch, though lacking in depth and replayability for those wanting a more involved metroidvania on the go.
A cute little game that's worth a bit of your time, as it only requires so little of it to show off all that it has to offer, but what is there is charming enough and leaves a very strong and positive impression.