What is the connection between Halo and Marathon!

[preetz16]

Ok its pretty obvious that there is some sort of connection between the two games, but what is it? The marathon symbol appears ALL the time and the are a few other similarities to the old shooter, but why? Does anyone have ay ideas?

~PReetz16

[Hugh_Jass]

Other than the fact that they were both developed by Bungie?

[kornrocks24]

the flood look like the alien guys