My mother has American Game - and they have super long legs and are much, much skinnier than your boy. Games were originally bred to be fighting roosters - so their heritage has made them more aggressive towards other boys. However, as people are breeding them for looks now and not for their original purpose they are becoming less aggressive.
Any chicken will flare hackles as they establish the pecking order. The problem with game roosters is they will kill other game roosters. Not the hens - only the roosters - because they will not back down ever. It isn't temper, its dominance. If your other rooster backs down then usually peace will reign. Right now we have two half game roosters in one cage, they were raised together and they live together just fine. During breeding season we let them out to roam around so they can get distance and they don't fight. Its when they are penned in close quarters they become territorial.
I have a few Sumatras - and I keep them in a mixed flock with a bunch of other bantam/half size chickens. The only time I saw my Sumi boy fight the lead roo was when it was breeding season. I now have two blue Sumatra boys and two black girls and a Silver Phoenix pair, as well as a bunch of others all housed together. I don't expect any trouble until next March - and then I will split them into breeding quarters to prevent a ruckus. After its over they all go back together again.
Any chicken will flare hackles as they establish the pecking order. The problem with game roosters is they will kill other game roosters. Not the hens - only the roosters - because they will not back down ever. It isn't temper, its dominance. If your other rooster backs down then usually peace will reign. Right now we have two half game roosters in one cage, they were raised together and they live together just fine. During breeding season we let them out to roam around so they can get distance and they don't fight. Its when they are penned in close quarters they become territorial.
I have a few Sumatras - and I keep them in a mixed flock with a bunch of other bantam/half size chickens. The only time I saw my Sumi boy fight the lead roo was when it was breeding season. I now have two blue Sumatra boys and two black girls and a Silver Phoenix pair, as well as a bunch of others all housed together. I don't expect any trouble until next March - and then I will split them into breeding quarters to prevent a ruckus. After its over they all go back together again.