I second the Skyrim reference ... damn good 5.1 design ... there's also quite a few good extra "mods" you can apply which improve the sound greatly ... specifically ambient/environmental sounds in outdoor areas ...
Also, Borderlands 2 is a joy regarding sound design (and just about every other game design discipline) ... it's truly a stellar bit of craftsmanship and game play ... most fun I've had in about 10 years. I'm sure the awards will flow for years; it's a truly outstanding bit of production (sound/game mechanics/combat system and especially the art direction and visual design...just a gorgeous bit of work) ...
I game quite regularly ... generally about an hour or two a day and way too many hours on the weekends ... my preferred means of play is my dedicated, desktop 5.1 speaker system ... a now aging but still PHENOMENALLY good sounding kit that at one time shipped with higher end Dell turn-key systems, the ADA995 surround system ... I bought this *RIDICULOUSLY* good sounding kit from a local computer wholesaler for a measly **$80.00** ... LOL ... about six years ago and it's still rocking like a CHAMP ... a super good sounding (separate mid/tweets in the satellites) and really throaty bit of kit ...
But I also share a house with two other humans and so I can't always use my speakers (differing schedules and what not) ... and during those rather frequent times when speakers won't fly ... I instead use this rather impressive bit of headphone gear released by Cooler Master a bit back ... the Storm Sirius 5.1 headphones ..
Seriously, there's a reason I turn a simple reply into a veritable infomercial on the merits of the Sirius 5.1 cans ... and that's cause they kick serious arse., Seriously ... if you spend some time in game tweaking the various settings in the Sirius control panel ... you can get some really freakish and good 5.1 surround sound out of these things ... mind you, they are *true* 5.1 cans with dedicated front/back/sub speakers in each cup ... at default settings they are quite fun and good but after you spend some time tweaking the various settings (mostly regarding bass response) then they become insanely good. This is definitely no software trickery or otherwise "Dolby" sort of trickery (which I find effective too and quite fun but no where near the true physical sense of space I get from the Sirius cans) ...
They are clunky, rich in plastic content, have lights that light up and what not, but they seriously work:
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Sorry.
PSA over ... nobody asked for all that but I've been so impressed with these things over the past six months or so that I figured I'd pontificate a bit. Cause I'm *real* picky when it comes to my computer gear and *especially* sound ,.. and pontificating aside? They are really worth checking out ...
ROCK!