Here it is - RTR Sealed Simulator.
It doesn't have guild packs, since I still haven't figured out what they contain precisely, and I'm a bit busy with everything since I just came back to London. Maybe I'll figure them out before prerelease, otherwise I'll just leave them.
Unlike for AVR and M13 times, for RTR it seems other websites have been much faster to add new set. Even Gatherer (which most sites use as a source) has RTR cards already, and it's still a few days before Prerelease, while Card Gallery I use for my source took a lot of time even after all cards were spoiled, so I couldn't update my simulator very quickly. Previously it was more than a week between Card Gallery and Gatherer.
If Gatherer keeps getting updates fast enough, perhaps there won't be much need for my simulator in the future.