You could use net limiter to cap the download to a lowish rate, giving you a reasonable speed and steady gaming
or try
Cfosspeed, bit more advanced than net meter but setup correctly gave me a steady 60ms ping whilst downloading at about 580KB/s (line will do 600 tops) It was much better than net limiter, gives a smoother game play with a great download speed!
I was thinking about http downloads there, if using torrents cfos is the way to go as priorities packets meaning the gaming had a good and constant connection with no spikes!