UX/RT is a new QNX-like OS based on the seL4 microkernel, with improvements in security and reliability over mainstream systems as well as several features they lack, while still maintaining a high degree of compatibility with and comparable performance to existing operating systems. Similar to QNX, UX/RT will be a single-personality Unix-like OS with fast synchronous kernel IPC, a lightweight IPC transport layer, services looked up through the filesystem, and an avoidance of vertical modularity for most subsystems. I will introduce the general architecture of UX/RT and how it differs from existing operating systems, describe a few notable features, and explain why I consider it to be the best balance of practicality, performance, compatibility, and features.