Here’s one,  Complete entombed with only fairies or other week character types and have all of them survive on hard-core mode.

heare is another one.
fight lord adrianas and kill him with out any character deaths at level 16.
one more.
complete bk 3 with out ever getting hit.
good luck.

...And what's the reward for completing any of those challenges?

@6: A virtual round of applause and appreciation, maybe?
@7: I would dare to say that that's impossible (at least if you mean Simeon's standard dagger), because you won't get far with
Spoilers
Lord Adrianus
End of spoilers
if you don't use ANY spells.

Play through all the inquisitor games (the first three) without using divine help once.

It possibly can be done, you'd probably need lots of magic defense and a shitload of strength

I have another one: Try to last ten minutes in Oh Shit.

A couple off the top of my head. Note that these are challenging, but not impossible.

1. In Manamon 1, defeat Yavin and Irroadium without losing any manamon. If a manamon faints at any time during either of these fights, you fail. For the sake of fairness, your manamon cannot be above level 60, and you may not use mythicals or copies of the same manamon (so no using six Mondevol or some such).
2. Beat Super Liam without taking any damage and without suffering any deaths. You may not use the bonus levels to accumulate extra lives, extra points or to skip levels.
3. In Super Egg Hunt, get over 320 eggs in Chicken Coop mode during a single run, without getting pecked by a chicken.
4. In Shadow Rine, beat the game on hard or higher without letting your health drop below 95%. The final boss's unavoidable attack does not count here (if this is the only damage you take, consider it a win). As an additional qualifier, you should not have more than 400 HP, and you should not have more than 20 attack or defense during the entire run (if those values exceed this limit, you fail).
5. In Code 7, play through the entirety of the game thus far (excluding the optional postgame Muffin levels) without failing a single puzzle even once. Failing a puzzle refers in specific to when you die and have to start over, so the tricky password puzzle in episode 2 does not count as failure. In addition, you must earn at least 50% of all listed achievements during your run.
6. And finally, in Paladin of the Sky, beat the entire game without dying once (resetting when you're about to die counts as a failure). No cheats or exploits allowed, for obvious reasons. For an additional challenge, you may only fail a total of twenty dragon strike scrolls, including those in the fights with Stella and Infected Cruelclaw, during the entirety of the run; if your failed dragon strike scrolls ever reaches 20 or higher, you fail.

Now obviously, you can adapt some of these to more adequately match your skill level. If the Paladin one is too hard, allow yourself fifty scroll fails instead of twenty; or if Code 7's challenge is too easy, try getting twenty-seven achievements or more in one run, while still making sure not to die. If you want to jack the Super Egg Hunt challenge difficulty, instead of avoiding being pecked, you would instead have to ensure that you get pecked at least one time. And in Shadow Rine, how about beating the game (including the after story) with all items with the same caveats as above (i.e., health never goes below 95%, same restrictions on stats, etc).

To be perfectly clear here, I'm not saying I can do all or any of these (though I can actually do a few of them, I won't say which). I think all are at least within the realm of possibility, though a couple of them are murderously tricky.

But to be honest, I wouldn't blame anyone for just flicking past all this stuff. There's no real incentive for such self-imposed challenges except bragging rights.

@jayde, those challenges sound fair, except the paladin one, since I can't even beet the game, lol.
the reason for that though is that I'm using an external key board and it's causing enough lag to make a certain fight impossible.
as for shadow line, that sounds easy enough, I'll open up a new save and try that soon.
as for why anybody would do these, it's the same reason people try to get achievements, which is that like I said above, a game gets boring after a while if you have to do the same thing.
these challenges are meant to provide a variation.

My current record in Chicken Coop is 331, but I've actually gotten higher than that in the past. I think my highest ever was 378, but that was insanely, ridiculously lucky, and I wouldn't ever put a challenge that out of reach. I routinely get 300+ in Chicken Coop though. It's not hard if you make a conscious effort to kill chickens and nab clocks, and don't keep treading the same ground you've already run across without first having spawned more eggs.

That's completely doable, as far as I recall, but you're apt to die once or twice, because ghosts have a habit of spawning randomly while you're in midair, and the Gray Lady herself teleports, also at random. I was at first tempted to buy that game, because some of the sound design is decent and I thought it might be a fun challenge. Then I watched a playthrough, listened to all the cheap deaths, and saved myself thirty bucks.

Just skimmed through the topic and can't motivate myself to even try any of that