These are the hints for Christmas Eve and Christmas Day. Hints will resume as usual afterwards.
Hint #5: Codename: Gordon (a side-scrolling shoot-em-up) was inspired by Half-Life 2 (a first-person physics simulator/shooter). It is available for free on Steam.
Hint #6: Street Fighter (a competitive fighting game) met science fiction in a seedy bar and the two produced Street Fighter 2010: The Final Fight (a side scrolling punch-em-up).