Since I'm now on the store's site, I figured it was prudent to upload the version of Rules of Engagement that I've been toting around for a while. My understanding is that my brother-in-law and one of his coworkers at Volition have updated the previously published version for 5th edition. It's reasonably similar to the one that was posted earlier.
Some notes: this is generally considered a work in progress, but I think we've been playing it as-is for almost two years without changing anything. The "unusual conditions" are fairly untested, and they can really unbalance a game. I only suggest using them if you're playing a "for fun" game. Having three Vortex grenades rolling around the table can be fun, but doesn't help if you're trying to really face off to test your generalship.
Any feedback is welcome. Matt and Bryan have wanted to refine this, but the three of us are the only ones that have played it consistenly for a while. If you guys want to post on here any thoughts, I'll relay them back to Matt.
Oh, looks like I can't upload a .pdf that large. Here's a link instead: