I have a few ideas which would be easy enough to program and could extend the life of this game immensely:
First, could we have a massive 'randomized' dungeon to explore (similar to a Diablo 1 throwback)? 666 floors where the level appearance changes every 30 floors and have monster difficulty and/or mob size and elite/champion occurrence increase as you descend deeper into the Abyss. Maybe have an 'Uber" battle every 100 floors and an epic battle at floor 666. Each of these areas could be themed and stocked with specific enemies to reflect the theme of each range of floors. There could be waypoints every so many floors (maybe 15 or 30) to track your progress. These waypoints could be used to resume a previous game to avoid resetting to floor 1 each gaming session. This could all be added as an additional 'bonus act' beyond the four we have to choose from and would provide a great alternative to those of us who love a good dungeon crawl experience.
Second, could we have a survival type challenge? Maybe a secret portal to an arena where we would have to battle 100 waves or more of increasingly difficult enemy mobs (with elites spawning at the end of each wave 1-4/6-9/11-14/16-19 and a champion that spawns every 5 waves). There could be multiple arenas to choose from before entering (each with it's own variety of denizens) to add some variety. Have a 10 or 15 second break between waves for town portals to sell/repair/RR break. Maybe even have a handful of goblins simultaneously spawning every 25 levels (sort of a throwback to the original Golden Axe camp event) to give bonus items for those who can weather the storm.
Please, farming the same acts endlessly is creating stagnancy in the game and some good PvE alternatives would greatly enhance the gaming experience for all players.
Please thumbs up if you like these ideas and feel free to add more ideas of your own ... let's get some more content for the PvE players.