You can browse the list of games in the Entropy repository on the Web page https://packages.sabayon.org/categories
Scroll down that Web page and you'll find the different games categories listed. Click on each to see a list of the available games and a short description.
You can also use the Search box on https://packages.sabayon.org/
if you want to check in future if a specific game is in the Entropy repository.
I'm not particularly into games, but this guy reviews quite a few Linux games, some of which are adventure games and which you'll find in the Entropy repository:http://www.dedoimedo.com/games/linux_games_all.htmlhttp://www.dedoimedo.com/games/linux-games-best.htmlhttp://www.dedoimedo.com/computer_games.html
Have a look also at the Web sites Linux Games Data Base
is a fabulous point-and-click puzzle adventure game which is available for Linux, and well worth the price.
Battle for Wesnoth and Minecraft are Linux adventure games I see mentioned quite a lot on the Web, but you'll find quite a few others mentioned on the above sites.