(I tried "Blob" and "Pong", both don't work in Opera 12.10)
Of course I understand that a framework supporting certain browsers doesn't mean that any other program (demo) will work automatically, but for the purposes of demonstration, you probably should make sure that they do.
After all, browser support is just as much a feature that should be demo-ed as pretty graphics are.
(And I really don't understand, what is this thing people do in their JS code that Opera chokes on? I write JS code all the time and it generally works on Opera/Firefox/Chrome with no tweaks. The very rare inconsistency is usually when one browser is more lenient than the other wrt ECMAscript, so even when it "works in Firefox", it was code that could use cleaning)