I remember once a topic about challenges in IVAN and the various suggestions. I've decided to pull out my own challenge, slightly more realistic than some other proposed, ie. the following:
1. At the start of the game, you have to go to New Attnam, leave Kenny there, and buy at least two bananas at the shop. You need to eat both and dual-wield the peels.
2. Throughout the game, the only wielded weapons allowed are banana peels, single-handed or dual-wielded. If they rot away (you get a message "equipment broken!"), your melee combat restrictions are as for panic - no direct combat unless cornered, and even so, only unarmed.
3. You cannot deal damage by wands except for the Holy Banana. Non-damaging wands are allowed (teleportation, polymorph, etc.).
4. Throwing, vomiting, potions, armour, cans, all food and divine interventions are all allowed, if they do not break the above rules. If a god grants you a weapon, you cannot use it, for example.
5. Pets are allowed, but only as god-granted gifts, and even so, you are obliged to prevent them from following you. You may steal their equipment or kill them afterwards.
6. Any version of IVAN is allowed, unless they're your own overpowered mods. I personally picked IVANT for its longer UT, so that you can get more stuff and power before facing Genetrix Vesana.
Now, onto the most successful adventure I've had with the above challenge - behold, the story of Bananator.
I started out and did my duty of dual-wielding banana peels. I then descended the mazes of UT and got myself some armour. Alas, my banana peels kept rotting away quickly, and before leaving the UT, I had to return to Attnam three times. Damn bananas.
Dual-wielding banana peels does two things: Improves your whip skills, and trains dexterity naturally and amazingly fast. Ironically, I've also found a runed +4 whip on my way in the UT, but I obviously didn't use it.
Trouble (or, if you prefer, FUN) starts with enemies that take no damage from banana peels. These are mutant asses, large carnivorous plants, kobold chieftains (strangely enough, not kobold lords) and Genetrix Vesana herself.
My way of dealing with Jenny was first to pray to Silva to get an earthquake, which teleported her away, and then using a wand of teleport to clear the area near the stairs and quickly escape.
Then I went to Attnam, and then to the GC, and then I forgot to get myself fire protection and I stepped on a bloody mine on the second level.
(please note the naturally trained dexterity and agility)
I had some fun before that, and the restrictions force you to do some extravagant strategies... I invite everybody to join
I know that the challenge is a bit chaotic as it is, and some elements of it may be overpowered (for one, praying to Legifer). But I'll keep trying