There are no gaming laptops in for $400 unless you look at used ones. GTA V is the issue, CS GO you can play on a low spec system, but even then $400 is on the limit. Look for a used system with an 850m , 950m, 860m, 960m video card, you may be able to find one in your price range. 840m or 940m will also work but that is marginal for games like GTA V. A system with the AMD A10 CPU can also work as a budget gaming system for low settings in new games.
The budget is just too low for anything "decent" or "gaming" unless used.