Had a go at extending the forum to use a ‘onebox’ (one of those helpers that appear when you type in an address, like a sort of preview thing) for Steam things.
When you put a link on a single line, something like this:
http://store.steampowered.com/app/310560/
It comes out looking like this:
To add this I had to restart the forum software a couple of times, so apologies for that - hopefully won’t happen often.