How many 2D games exist that only use ASCII characters ( and no graphics ) ?

Only 2 games I can think of are ZZT and Dwarf Fortress.

Are you able to think of any more ?

http://www.roguebasin.com/index.php?title=List_of_roguelikes_by_theme

Seriously, there's a metric shit-ton of roguelikes out there that only use ASCII symbols. Some use tiles, sure, but the vast majority either do not, or offer tiles only as an option.

There is a pretty solid community of people making interactive fiction with tools like Inform.

There's also Ultra Business Tycoon III, which was listed as one of the top games of 2013 by Gamasutra

Seriously, there's a metric shit-ton of roguelikes out there that only use ASCII symbols. Some use tiles, sure, but the vast majority either do not, or offer tiles only as an option.

Roguelikes are huge, but they only represent one niche.

There are similarly huge volumes of other text based games.

Story-style games, eg: "You are in a maze of twisty little passages..." are still fairly common. They cover a wide range of topics.

Quite a few 'terminal' games are out there, including themes of air traffic control, star trek, and so on.

Then take a look at the web. You know all those little facebook games "What kind of movie character are you?", where you pick ten or so blocks of text and it tells you you are most like a stormtrooper or want to date Katy Perry. Those are also text based games.

They are all around you.

honorable mention

honorable mention

That must have taken forever to map out all the "pixels" for that !!!

honorable mention

That must have taken forever to map out all the "pixels" for that !!!

Its actually not that hard --

The way a game like that works is that it renders to a fairly normal pixel-centric buffer internally, and then there's a post-processing stage that converts the resulting bitmap-style image into ASCII text. The way the conversion works is that it breaks the bitmap up into tiles the same size as the font, and compares that tile against a set of tiles containing the font -- it chooses the ascii-font tile that's most-similar to the bitmap tile, and often accumulates the error, similar to how dithering works. For sufficiently-low internal resolutions, the mapping between the bitmap tile and ascii tile can be pre-computed in a table (with provisions for error-accumulation).

Its the same principle that block-based compression schemes use (jpeg, mpeg, and most video formats), except that the target tile-set is pre-determined by the font's character set -- those other formats first apply some heuristic to determine their target tile-set to achieve best results within a given bit-rate target or maximum tile-set size.

I've seen a version of Quake that rendered with ASCII text, although the relatively high detail found in quake, combined with its rather monochromatic color palette combine to make the ascii output rather hard do decipher.