Don't Look Back is a Flash platformer by Terry Cavanagh (of VVVVVV fame). Based on the Greek mythology of Orpheus and Eurydice, the goal is to find Eurydice's spirit and bring her back to her grave without looking at her while she's following the protagonist.
Rxser brings Eurydice back to her grave in record time.
PHOTOSENSITIVITY WARNING: There are flashing lights and strong screen shaking during the boss fights and when they're defeated, which may cause epileptic seizures and/or motion sickness to those affected.