I'm actually using rEFIt for the boot loader, keeping a small OSX partition, to install Ubuntu Server on the bigger partition.
Another company who colo's in our facilities uses OS X however for web application serving.
We use Ubuntu more-so for the support with MySQL's Galera cluster, usually we are a FreeBSD house.
That's just a testbench - most of the board you see there and the network jack are stand-ins for the giant board that they'll be putting a bunch of those nodes on.
Here's what the actual node looks like: https://www.scaleway.com/img/c1.fdf7.jpg
Backplane with nodes: http://www.cnx-software.com/wp-content/uploads/2014/12/OnlineLabs-C1-FrontBoard.jpg
It's a NavePoint 9U Wall Mount Network Server. The R220's will clear the front glass without the bezels installed but it was very tight at the back of the rack. I moved everything back a U and left the back of the rack off, which seems to be working out well.
The fans on top of the rack are loud but they move a ton of air.
The two 5P550R's at the bottom of the rack protect everything in the rack on the electrical side. I have an ethernet surge protector between the rack and the AT&T fiber termination (located in a separate smart panel.)
A game such as Universe Sandbox would certainly benefit from double point precision because much of the games purpose is to calculate the orbital paths of celestial bodies.
I'd want something that can slide out, otherwise it's not any better than what I do now: just use a loose monitor/keyboard that I have to hold awkwardly with one hand or on the ground. This is what I want, but can't justify paying that price:
At some point I might look at custom building something using a regular monitor, keyboard and mouse (which could probably be done for under $300) but it's one of those things I don't think about until I need it.