M.E.D.I.O.C.R.E. M.E.R.C. wears its XCOM inspiration proudly on its sleeve, and as its grim gray militaristic cast of characters would heavy-handedly growl, that’s a tactical error. Because it means I have to open this preview of its Early Access build by saying this: M.E.R.C. isn’t as good as XCOM,…