Right, the index.html has the canvas size, but I didn't want to ask users to paste in yet another piece of text. I've opted to ask for the height and width because there are some additions I'm planning to add regarding them, like a fluid wrapper, so the game could resize when used with a responsive theme.
The height/width are indeed contained in c2runtime.js as well though. It's just a tough process of grabbing that data from the runtime as opposed to index.html.
It seems to me that all the handwork required by your form/tool could/should be automated by a generalised WP plugin for C2 HTML5 exports.
Yes, it could be automated as such, though the dynamic between these 2 plugin concepts is different. As I mentioned earlier, if a developer wanted to release their game, let's say it's just a simple tic-tac-toe game, to the WP community, they could package up their project with the tool and do so.
This would be preferable to them giving instructions on installing the generalized WP C2 plugin and then downloading and installing their zipped project, for example. It's just a step easier for those wishing to use just that one game/app.
Incidentally, I just threw together a WP plugin that allows for easy integration of Inform 7 games and it provides the sort of generalized support you're referring to here regarding C2. The thing is though, it doesn't currently support games with extra resources, like images and sounds. That actually is the tricky thing about this type of C2 plugin too.
It takes quite a bit of consideration as to how to store such resources in WordPress. One would most likely use the Media Library to store resources (after unzipping process) and then store the locations of the relevant files in the database. I'm pretty sure that would be the optimal way to go about it, though I've not yet tackled that.
EDIT: I only just realized these resources could be stored in sub-folders in the plugin folder, though I'm not so sure of the implications of that. The plugin would need to provide a robust uninstall process as well.