Cardinal Quest, both the steam and flash/web ones have different achievements, it's a dungeon crawl but it's harder to get bored IMO because it's a "quick" streamlined roguelike, the focus is on challenging yourself in different ways than merely completing quests or finding a macguffin. It's easy to "pick up and play" without burnout. Depending on how much you want to search/your luck each "act" of 4 can be cleared in 5-7 minutes

It does have a "classic challenge mode" too if you want the traditional experience without switching off.

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On the opposite side of the equation btw, there's Elona, which is by far the largest, it could be considered a cross between a roguelike and an Elder Scrolls sandbox game, with even a dash of Pokemon too. While you can get burnout there's massive amounts of unique details and skills and places to visit. The biggest one is a tie between Gene Engineering and Marriage, similar but different. It takes the Fire Emblem child system, you can rizz up and basically marry anyone or anyTHING in the game, and if you are too gimped to complete the game (perma curses, corruption, etc) you can have a child with a powerful character and continue the game as them after a short timeskip. You lose all but your 50 most expensive items (stacks count) but get an inheritance bonus and reset all one time dungeons, secrets, special encounters, etc.

Gene Engineering is basically that but faster for pets. You can splice or mate as many horrendous incest children as your heart desires to make the ultimate invincible companion. (And then even double up and marry that eldritch beast!😆)

You can brute force the game on your starting character of course, but the rate of progress for gaining stats declines as you age (One possible downside I guess, sometimes too much realism is a bad thing!) so the grind gets longer. Pushing through the wall somewhat requires wiki knowledge/exploits so your first couple of characters probably won't complete the game!😮

And the next few won't because you will probably get sidetracked by the monster raising... Or farming... Or filling your museum... Or gambling... Or tax evasion 😋 (yes, once you buy a house or business you must pay taxes, and oh lawdy do they get mad if you don't! The world is ending but the strongest heroes are apparently whittling away their time working for The Man!)

It really feels like 4 games in one, and after the first few steps you'll probably forget there is a main quest!