Devil May Cry 3 and 4's Bloody Palace modes. I just don't have the patience for either one anymore. The former has 9,999 floors. Even if you skip every 100 levels, it can still take 2 and a half to 4 hours to beat. DMC 4 has a pretty unforgiving time limit, if you don't know how to kill enemies fast enough and take no damage while doing so on each floor. DmC allows you to disable the timer, though even with the timer, it's pretty forgiving. DMC5 on the other hand, allows you to practice on floors you completed. Not to mention the time is much more forgiving. Really forgiving. Making almost all the other Bloody Palaces obsolete.