Dungeon Assault is the hack-and-slash bastard child of Harem Collector. It was built as an experiment by NoMoshing to make and test code which is now used in the Random Daily Quests.

It can be downloaded from here.

Dungeon Assault is a roguelike game, except you can save it every time you pass a level. You cannot retreat to an earlier level and there is a finite amount of enemies, which limits how much XP, Sil, and items you can acquire. There are 15 levels total, with the last one being the boss fight.

Beating Dungeon Assault gives you a code you can enter at character creation (or the code input machine at the Manor) to get a special item.

Dungeon Assault Tee: Body Gear slot equipment. +15 Attack, +1 Defense, +15 Magic.

The easiest way to beat dungeon assault is to fight every enemy on every floor and explore every room to get money exp and items,  there are shops later that can get your equipment and position, always sell your old equipment once you get better. The succubus is a tough fight but as long as you fought each monster and have ok equipment you should be fine she casts sleep a lot dispel herbs are very useful and revives in case a companion dies, she has a very high magic defense so just mostly use physical attacks  and you should be fine