This is a neat idea for a game. The theme is silly, and it works well. Having the runner be slightly difficult to control when moving quickly is good too, since that makes things a little more dangerous. Especially when combined with the most-but-not-quite stationary guards. I like the art style as well - it all holds together quite nicely.
As for interesting features to add to the game, I think you could build a little more around the central mechanic. Right now it's just avoiding guards and collecting points, but maybe you could also have the other streakers affect your score, or perhaps there could be stunts you can/should do to interact with the crowd. A high score table would also be a good feature, since it's all about the score attack.
Others have mentioned the lack of sound and music, and I think that's the big thing right now. Having some background noise, a cheering crowd etc. just by itself would go a long way towards making the stadion feel more alive.