Gamerscore Service

Hey don't know if this has been done before but I was thinking about doing a Gamerscore service, i've got games I could get Gamerscore on and was wondering if anyone would want it? Like completing Cod 4 and stuff.
Is there any way I could do it safely? Because I know i'm a leecher and people will jump to conclusions so if theres a way we could do it so it's 100% safe on your side let me know? I wouldn't know what prices or anything either.
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