After the success of OMF: 2097, Rob moved back to Panama City. Ryan, who had a computer company in Tampa with Jeff Butler, stayed there. Ryan helped Jeff get a job in the company he was working for. After some time, Jeff got a job with Verrant (makers of Everquest) and helped Ryan get a job there. Then Jeff left with Brad McQuaid to form their own company... Rob rented a house and began to work on what was then called "OMF 2". It was supposed to be OMF 2097 with more bots, arenas and cooler moves and some other enhancements. Rob paid Ryan for about a year to enhance OMF: 2097. Then they (Rob and Ryan) realized the game needed to be 3D. Rob needed a team to work with in Panama City and Ryan had a family in Tampa and did not want to move back home and so he got a job and started working apart from his brother, Rob. So he scrapped the project and began to work on OMF: BattleGrounds (OMF: BG), a fully 3D fighting game for the PC. When Rob turned to Epic for help with the 3D version (he requested to use the Unreal engine), Epic was not cooperating (they denied use of the Unreal engine), so Rob parted ways with Epic to make his own game engine (Phoenix). The engine was made once, then trashed and made again. Then Rob joined forces with Edgar (DE's ex-lead programmer) and together, they made the engine that the game uses today and that's when the team for OMF: BG began (1999). The game first used an OpenGL renderer, but that was later scrapped because of some limitations and unsatisfactory performance. The game uses a Direct3D renderer (requires DirectX 9 or better installed, but will run on a DX7 card) and has no OpenGL support.
Understandably, some OMF fans aren't happy because OMF: BG is not OMF: 2097 in 3D. It is very different. It contains new bots, and all the bots look different now. In OMF: 2097's story line, robot fighting was not quite a sport, but 20 years later, in OMF: BG it is a megasport. Quite a few characters from OMF: 2097 still remain. Among those are Raven, Steffan, Milano, Jaqouline, Steel Claw, Ian and Ibrahim.
OMF:BG has 12 arenas, 57 pilots, and 8 robots. Three arenas made it into BG from 2097 - Desert, Power Plant and the Fire Pit (Inferno) arena. Those newly added are Blade Pit (similar to Danger Room), Dante's Chasm, Neo Vegas, Arctic Depth, Space Station, Mt. Haishiro, Pharaoh's Fire, Blast Furnace, and Laser Ball. Only the Jaguar, Chronos, Pyros, Katana and the Gargoyle made it to BG. Others had to be dropped because of problems making 3D models of them, such as the shadow and flail. The shadow makes replicas of itself and so it will slow the game down drastically and the flail's chains are not very easy to do. New bots that have been added are the Force, and the Mantis. Since, the game is in 3D, a lot of new strategies and moves had to be changed and added.
One thing that I really like about the game is it's music engine. The music changes according to the mood of the game, that is, when you are winning, there is one tune, when, you are losing there is another, when you're even there is another, etc. OMF was released on the 17th of December, 2003. Unfortunately at release, the game had some serious bugs due to being rushed and received poor reviews as a result. The game has since been patched but the damage by the poor reviews was permanent and the game did not sell well. OMF:BG is occasionally seen at bargain bins or other discount stores. You can also buy it online through Amazon or eBay.

Official System Requirements:
Intel Pentium III or AMD Athlon 733MHz or better
128MB RAM (256MB recommended)
1GB Hard Disk Space
8X CD-ROM Drive
3D Accelerator Card w/ 16MB RAM (32MB or better recommended)
56K Modem or better for Internet play

My Recommended System Specs (unofficial):
Intel Pentium 4 1.6GHz, AMD Athlon XP 1800+ or higher
512MB DDR RAM or better
1GB Free Hard Disk Space
DirectX 9 capable 3D Accelerator Card (Radeon 9500+ or GeForce 5600+)
256kbps down or better for Internet play

For more information about OMF:BG, check out this FAQ by Robyrt!