I'd chime in on a lot of what has been said. I second getter's proposal of Shiren. Very professional (of course, that's null if you can't stand the manga style). I'm also a fan of Oryx's tile sets for Brogue and IA. In addition to being very well done, I like how they are conscious of the RL tradition in being very iconic, rather than realistic (Oryx, as always on the cutting edge of RL graphics.
). An example of this is how they are monochrome, and as such possible to fill with different colors. I never much cared for Crawl's tile set or Gervais' tiles, personally. It always felt to me as if they were aiming to be too realistic, but skimping on the details. In addition to being slightly hard to make out, they would need animations and facing to convince me. "So, I'm confronting this meticulously hand drawn troll in melee, but we're both facing east? Ugh."
It's very much a question of taste, of course, and asking that question here, one is bound to get a lot of people who prefer ascii over sprites/tiles. For one thing, an ascii display lets you see more of the map at any given time. Consider the upcoming tiles for ADOM. I think they look pretty good, but they'll surely leave the player with a scrollable map, whereas ascii ADOM fits the entire map to one screen. So Biskup is sacrificing a nice feature to fit the tiles on the screen. On the other hand, you can more easily convey more kinds of information with graphical tiles (explicit facing, health bars, whatever).
To praise ascii some more, ascii maps can be really pretty in done well. Ascii has the potential to create many varied and evocative worlds without requiring huge amounts of manual labor (chugging out new sprites). Just using typography, you can have outdoors and indoors, elemental levels, as well as regular dungeons – and, I think, still convey in the player a sense of wonder at entering a level with a "new" look. Having hacked your way through a dozen "grey #"-themed levels, over hundreds of deaths, and suddently coming upon a green level, you'll surely experience a feeling of entering a biotope teeming with chlorophyllic life.
The previous paragraphs, of course, is typical of a "hardore" RL player, I think. We're the kind who freeze in our chairs at encountering a "U" for the first time. The trend of increasingly graphical RLs is something I personally welcome. It's bringing more people to the genre, for one thing. And a lot of people are doing good work to advance the genre.
Some that haven't been mentioned so far in the thread …
Legerdemain would be an example of a game that does nice ascii maps. I never got very far in the game, but just starting to explore the overworld is very exciting because of the artistic landscapes. Of course, the game has fixed maps, so the developer has had a chance to design them more thoroughly than in a typical RL.
Mercury. Like IA, here's a graphical game thatt tries to retain the iconic feel of the RL tradition, using pretty letters and abstract symbols. I'm sure some find it too baroque, but I personally like it. It bears noting that Mercury seems to try to make the visuals part of the game mechanics. Better players get to assign items and monsters for other players, choosing an appropriate icon as part of the creation process. (Correct me if I'm wrong, I only tried the game once, and didn't get the networking part to work.)
Vapors of Insanity. I'd like to mention it, since it's another graphical game with a unique approach. The tiles very much aim to be iconic in the sense of IA or Mercury. They tend to get a bit tiny and difficult to make out at times, but it's all part of the truly wonderful experience of VoI: finding books, revealing new pieces of lore and new skills (taxonomy is wonderful)
/me love
jasonpickering's games. Crisp, cool pixel art scaled to a palatable size, and with rule systems to match. Jason's games being always in very good style
Vicous Orcs. I love the shout function in Jeff Lait's Vicious Orcs and Smart Kobolds. At random intervals, avatars on the screen get a speech bubble that hovers over their position for a few turns/seconds. Lait uses them very effectively to convey the feeling of the scenery (kobolds taunting you, even after you are dead, etc). Vicous Orcs also have differently colored levels, which is a nice and affordable trick to paint the scenery a little.
That's all I can think of now
As always,
Minotauros