Arcilator is a new cycle-accurate hardware simulator in CIRCT that eliminates the need to export the design to Verilog and use a third-party OSS or proprietary simulator. In this talk, we will discuss the design and implementation of Arcilator and the novel IR that connects CIRCT's HW representation to LLVM IR. Moreover, we will show that it already delivers performance comparable to Verilator, explore future developments of Arcilator, and discuss other tools where the new IR could provide advantages.