I've really been enjoying this game. It's beautifully designed and a pleasure to play!
I had never played Rogue before encountering it on the iPod Touch. However, I did play Moria very intensively many years ago - as you probably know it's like Rogue, but with much more to it - I still think Moria is the greatest computer game ever made. I tried Angband and its variants later on, and while the extra bells and whistles they added were fun, I didn't feel they really added to the gameplay.
So basically, my ideal request would be to make a version of Moria (or a roguelike game along those lines, with that amount of stuff in it) for the iThing. That game, recreated in the stylish way you've done Rogue, would be absolutely incredible and blow everything else in the app store away. I noticed a post or two suggesting that a more advanced roguelike game might be on its way, and that would be fantastic.
Failing that, there are a few ideas I'd like to see in Rogue if possible. I'm aware that many of the things that make Moria great - such as more character stats, character classes, different shops, and the rest - would probably spoil Rogue. I rather like the "jump in and play" feel of Rogue, no need to mess about creating a character and all that. So I'll restrict myself to some of the simpler things that I think would enhance Rogue as it is, without losing its distinctive feel, and keep back all the other stuff for my request for a version of Morialike game!
(1) Search mode. Turn it on and you automatically do a search every step. This would save a lot of hassle.
(2) Please, show the walls of corridors as well as rooms! It looks odd to have walls around rooms but not corridors. Also, for those warrens of corridors, it is useful to see what's a real dead end and what's just a tunnel you haven't walked all the way down yet.
(3) Monsters should be able to use secret doors without you having to find them first (or at least, intelligent ones should). Of course, if you see a monster emerging from one, you will know it's there.
(4) There should be some monsters (ghosts etc) that can move through rock. Admittedly I haven't got all the way to the bottom of the dungeon yet so perhaps there are some waiting for me!
(5) There could be many more varieties of monster. For example, there's just a "Slime" monster. Why not use the same graphic, but perhaps with different colours, to represent many different kinds of slime, with varying abilities and strengths? And so on for the others.
(6) It's incredibly confusing that AC is measured on a descending scale but armour is rated on an ascending scale.
(7) How about the ability to mine? There could be different kinds of rock, representing different degrees of hardness, and containing gold seams that you could dig out. (I just nicked this from Moria but it might be fun.)
(8) Character abilities - e.g. fighting, ranged weapons, magic item use, etc. Each time you go up a level, your abilities might improve, representing your skill at those particular activities. Rather than mess about with assigning skill points and stuff, why not have the abilities improve to reflect gameplay so far. For example, use your bow a lot, and next time you go up a level your ranged weapon skill will increase.
(9) Timed rests. Enter a number and your character will rest for that number of turns (stopping if a monster appears, of course). Or have the option to rest until fully healed.
(10) Examine icon. Tap it, and then tap something on the screen (tile, monster, object) and it will tell you what it is. That way I don't have to go and pick up that potion only to find it's a useless one. And I have some idea what that unfamiliar creature is.
(11) Some sort of indication in-game of the relative power of weapons. Is a two-handed sword better than a katana? It would be nice to know when I'm wondering which one to wave at things.
(12) Variable light radius. Why not get some item that casts light for two squares, or even more? (Actually I think these may already exist deeper down - but I think there should be more options for casting light, given that without it ranged weapons aren't much use.)
(13) I think that when you cast a light spell in a room, any sleeping monsters there ought to wake up.
[EDIT] A couple more...
(14) You can wield a new weapon without having to remove the old one manually first - the game swaps them for you. So why can't you do this with armour?
(15) The "tap the weapon icon to shoot" feature doesn't seem to work if you're using D-pad controls.
(16) I really like the little touch of finding graffiti by your previous characters! But it always seems to be only your *last* character. And I've found his scrawlings on much deeper levels than he ever got to. It would be cool if the graffiti were by all of your previous characters, and they appeared only on depths that those characters actually got to - so if you get to a deeper level than ever before, you won't find any. (It would also be cool if the graffiti said various different things...)
(17) I also really like the little touch of finding your previous character's corpse and being able to fight it. It would be nice if, after defeating it, the game specified which previous character it was ("The nametag on his clothes says '...'" or something like that!).
Thanks again for a really smartly designed version of this game. I'll be watching out for anything else you produce.