captain carot on 15 November 2015
PS2 had a userbase almost as big as PS360 have together.
About Halo sales:
Halo 3 was the (retail) peak. Roughly doubled Halo 2 sales. But at that time there weren't that much other FPS with a really great MP. And it had the effect that many early games on a platform share.
Look at GT, MGS or FF. FF VII sold way more than VIII and IX. And FF X again sold better tha the late FF XII.
So with some usual effects for later sequels on a specific platform you can't really say that Halo declined after 3. If there's a decline it happened on Xbox One.
