As ex-game dev this is all right on the mark. Back when I was in gamedev the "code" checkout was ~160gb. The "art" checkout was ~500gb and the raw repo size was on the order of 3-4TB.
Last I kicked the tires proper on most SCM solutions Perforce was the only one that could handle repos like that and provide locking so that people won't blow away binary files.
1. Huge files - a distributed VCS will not handle versioning them in a space-efficient manner without hacks like LFS. Plastic SCM says they handle huge files, but you want to investigate this closely.
2. Locking files - Game assets will usually be binary and non-mergeable so you need to be able to lock them so that only one person is able to edit at a time. PlasticSCM seems to have this handled according to their website.
3. Disk space - Watch the pricing for disk space. 5GB is nowhere near sufficient for a game of reasonable size. Seems reasonable at $20/month up to 100GB, but make sure you understand what you'll get. They allow for a local server, which might be useful for a company (or if you don't mind setting up your own servers).
If you're a solo or small-team indie, you can probably get by using anything. git, plastic, svn or perforce. perforce even has a cloud hosting solution.
There is a reason Perforce is widespread in the gaming industry and it's not because we're a bunch of mouth-breathing morons stuck in 2005.