This is what the ray caster looks like, generally speaking, with pretty much nothing but dumb slightly animated smiley faces squashed and colored in different ways. The smileys could be anything, but I'm a game programmer, not an artist.
Arrows or QWEASD: Move around
Home/End: Go up/down
PgUp/PgDn: Look Up/Down
Right-Click: See daylight/darkness modes (currently only works on the map for some reason).
Click on map: Teleport
Written using the Flex 2 SDK in Actionscript 3. Requires Flash 9 or higher.
This is an older thing that can be found in the 'unit tests', which is Flash 8, and suitable for cell phones. It just slaps up sprites. My ode to 'Dungeon Master', so to speak. The technique is much simpler to understand and could be a decent base for a beginner to make a dungeon crawl. Works well even below 10FPS (though the key response becomes sluggish, but on even a low-end PC it could do as many as you like.
This is the little unit I used to develop the ray casting from camera to terrain. Click to set a start point, then drive with the arrows.
This is the path-finding unit. Most of the stuff is buried in the context menu (right click). Left click mostly sets starts/ends and resets.