Or you can try to make certain changes, so it wont be a copy right. For example: Skulls in ODST and Halo. To make the game harder. You can change that into Artifacts (that are around the 12 missions to find in the corners). So next time your play will be different if you put a Artifact active.
Are you getting the excact units from those games? Maybe can change that into zerg units.
Change the medal system: into brons * three tiers etc.
Just, modify it enough to the basis of Blizzard races (but make it so that people will see the resemblance of it enough), so you wont have to worry about the Copy right because it would be a disapointment to all the hours you invest and in one day to another you will get the message its deleted because of Copy right.