Treasure Chest Corps - Fight Demons to Restore the Barrier by WhitePeach is an RPG eroge that's fairly appealing. The RPG mechanics are nothing new, but the art style is good, and it boasts some top tier waifus that can either win battles against invading monsters, or get raped. 

Per the game page:

[Story]
From long ago, monsters had appeared in this world,
and had begun a war with humans.

This is the Lam castle within the Heavens Kingdom.
The barrier tower that was protecting the town
suddenly stopped working after an unknown attack.
The demons quickly invaded.

To get the barrier tower up and running again,
Limly the scholar and a small group of adventurers
was hired for the job...

[Game System]
Grow your group and complete missions together!
Different equipment available!

Fight with your comrades to win back your peaceful lives!

The story is typical fantasy fare, but the game is side-scrolling RPG goodness with cute and sexy waifus, so it gets a pass. Players use WASD to move a selected character around to fight. It's also available in English.