Operation Fix the Wall - Episode I RPG is a singleplayer adventure map. It's stylized as an RPG and guarantees at least 3 hours of playtime, usually taking players even 6. Many of its custom features are:
"My autoclicker doesn't work!" - said every 1.8 PvPer
That's not an issue! Because with a fully different combat system you can spam the sword (but it won't do anything). Take turns, attack, usespecial abilities, and even turn into a ghost! All within a very easy to understand system.