I think "you" should be left out since it can potentially be rude, and I think the subject is implied here
FINE
そのゲームで%1はブロック建てる (%1 build blocks in the game)
no but seriously i doubt people are going to get super offended if you dont know they're name in this sense
also since we can just imply 100% of the garbage (like you say so) then all we need is
建てる (build)
there. simple, perfect, complies with char's rules, yknow.