A few that I've enjoyed:
- exploration and puzzle based platformer, with an astronaut encountering bizarre ecosystems in a martian cave system
- retro-styled RPG
Spider: Secret of Bryce Manor
- you're an actual spider, chasing down various bugs that require different tactics
Might want to keep an eye on the Humble Bundle site, they sometimes have some good Android bundles.
if you want old adventures, install ScummVM and you can play old Lucasarts and Sierra games (have to supply them yourself, but there are a bunch on steam and gog these days)