I've published my Pac-Man clone! It's not 100% complete, but this was just a learning exercise, and I think I've gotten enough out of it.

The bits that I didn't do:

• Music: I wanted to record some simple background music in a particular key, and record the sound effects in the same key. They would combine produce a randomly generated soundtrack. I recently attended a talk at Freeplay by a guy called Stephan Schütze, who had lots of interesting things to say about procedural music generation. I may revisit this idea in a future project.
• Artwork: There are some elements that I didn't bother doing (mainly the bonus symbols, which are represented as plain white squares). The ghost artwork is pretty inconsistent, too - ghosts look totally different when frightened. I would probably have fixed this, but my trial Photoshop license expired. (Do you know how much that thing costs nowadays?)
• I skipped some behavioural details, like the way ghosts jostle around in the house when they're waiting to be released.

Other than those, it's a pretty faithful implementation of the game.

There are some technical decisions that I would make differently in retrospect. The following (non-exhaustive!) list outlines some choices that might have overcomplicated things:

• Code structure: Programmers have a tendency to look for patterns and generalisations in code that can be re-used. In my case, I wanted to keep the engine code as simple as possible, and pushed all the behavioural bits and pieces (particularly the ghost releasing and mode switching behaviour) down into objects (i.e. DotCounter, ElroyCounter, ModeSwitcher and ReleaseTimer). I don't think I hit a particularly sweet spot of abstraction by doing that – it would probably have been nicer to keep it all nearer the surface.
• Movement: I got overly concerned about actors moving in sub-pixel increments. That is, the ghosts and Pac-Man can have speeds of e.g. 1.2 pixels/frame, but you can't draw inbetween pixels on the screen. I came up with some rather complicated code to accumulate fractional pixel amounts between frames, but it would've been much easier to store the raw values and round to the nearest pixel when drawing. Check out Actor to see what I mean.

There are plenty of other warts in the code, but it works OK.

The playable version is at http://www.harto.org/wheel/pacman. It works in recent versions of Firefox, Chrome and Safari (without sound). The source is at https://github.com/harto/pacman.

Let me know what you think!