1)Add scrap/cube/what ever you want currency system ,witch would allow humans to take loot from poor dead robots in form of bag with stuff (boring) or the robots mutilated bodies themselves and later do their scary human things with them ... damn those humans! Also it would be fun to watch filthy humans trying to get body parts faster then those cool and fancy looking janitor bots :D. This currency could be used to repair human's robot body or to customize it's equipment (customization is a second idea).
2)Judging by the fact that all robots and weapons are made out of cubes (btw never thought that the sword out of cubes will be so sharp:D ) it could be possible for humans to customize their equipment like adding or removing cubes from original weapon and armor models (of course with limitations cuz you don't want any humans running around the arena with 69 meter long d... I mean human body private area part or transforming their small robot bodies into SPIDERTRON OVER9001(oh my emperor the first one and the second one combined 0_o....like in each spider leg...wow ). Also if you are not planing to add that kind of customization at least you can make it possible for humans to design their own KILLING MACHINES!!!!
2 plan-B ) Add purchasable preset weapons and armor.... you can do that .... I guess ... if you are.... A TOTAL LOSER cuz that's boring as HELL!!
2 plan-C ) Add both... that's ok.
3) Add a banana... I'm hungry.
4) Multiplayer.
5) If you want to "continue" this random human at the start theme you can add random passive skill at start or one of already existing ones.
6) First person mode? idk.
Sooooooo I guess that's all my ideas for now. I could say more about customization ,but your processors are probably already fried like humans if you would add fire traps :P ,plus I'd rather wait for updates.
P.S.
Every point except 3-rd is optional XD...seriously.
Sorry for all the grammar mistakes ,English is not my main OC language :D