To make a futuresport, take a modern sport then add ultraviolence and perhaps motorcycles. Imagine hockey with razorpucks, cycle polo with motorcycles and warhammers, or football where people don't dive to the ground when touched but rather give the other player a damned good hiding. That last one's not far off the idea of Soccer Rage [official site].
With no off-sides, substitutions, fouls, or any rules beyond "kick the ball into the goal" really, Soccer Rage is part football and part fighting game. Ungentlemanly sportsmen can check it out now on Steam Early Access.
Oh aye, your robomen can attempt to simply kick the ball around if you really want, but it'll go a lot better if you deck some of their team. Along with classic top-down footie, it has classic side-on fighting game battles. If you are not fascinated by this combinations of genres, well, clearly you have insufficient passion for futuresports. My friend Holly Gramazio gave a talk about deadly games a few years back, and I think it might help you.
Developers Stamina-Games expect Soccer Rage will be in Early Access until October while they gather feedback and add new things. They have a timeline of what they plan to add and when. Right now, it'll cost you £7.14 on Steam.