I've always liked this song. I can't remember where I heard of Oskar Schuster, but his music reminds me of this song, for example, this track: https://soundcloud.com/oskarschuster/vleurgat-new-album-demo... Here's his SoundCloud and his website
I absolutely love piano/keyboard driven music as well, from classical to modern rock. You ever find that it makes you want to learn piano? Maybe it's just me, but everytime I listen to something like Avril 14th I want to go out, buy a keyboard, and commit to practicing enough everyday until I can play it.
Yes it constantly makes me want to learn piano. As a matter of fact I plan on buying a keyboard next year and starting piano lessons. I don't think Avril 14th is actually played on a real piano (probably MIDI or something), but still just the way it sounds makes you want to be able to fill a room with those sounds.