We thought it was a good idea too, but sadly it only lasted around 5 or 6 rounds like this one but that was because the entire site was discontinued. What I had going at the time was a month long compo called "OVGMcon" Or, the "Original Video Game Music Contest.. Those themes were more detailed and specific. One of the last ones we even decided to make a fictional game sound track where each person would take a different type of level theme and fit it into the original story somehow.
Our coolest one was for a fictional game I came up with called "Sawtooth The Radical Beaver" LOL. That game's "story" was that basically you start out as the character Sawtooth the beaver who is a radical shredding keyboardist who lives in the forest with other animal friends you meet as the game progresses. (Which is kind of awesome considering there is a "sawtooth" type of synth sound.) Anyway, he is trying to start a band with other forest creatures in order to raise enough money to keep the home of himself and his animal friends safe from big wig developers who'd like to tear it down. So, you go through different levels gathering different band member friends to help you on your quest, as well as different artifacts to construct or improve your bands instruments and sound in the main game so that in the bonus rounds when you play concerts and stuff you raise more money to put towards getting your home saved and reserved as a national park before the developers get the permit to tear your home down LOL. We had a forest level, a cave level, even a saw mill factory for the last level and some others I can't quite remember (Maybe a bonus Jam session Level? LOL). But that was our last theme before we disbanded, and I was always sad I couldn't start it up again. It resulted in some of my best music because we had so much time to compose 
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I even still have some of my songs from that compo:
This was for a futuristic racing game: https://8bc.org/music/Jredd/Darkened+Path/
This was for a highly detailed space ship mission where it crash lands on a planet and stuff happens: https://8bc.org/music/Jredd/Into+the+Unknown/
And this was for an RPG themed setting which had a super long story that I can't quite remember: https://8bc.org/music/Jredd/Moonlit+Myst/
As you can tell, this compo isn't chip...but it was video game inspired 
Sorry for the ridiculously long post...but it brought back old memories.
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