May I ask what circuit simulator game? I've attempted something similar with my very limited and hobby level hardware knowledge in Virtual Circuit Board and I learned that it would take me much longer than a weekend, heh.
I also made my own assembler as part of learning the ISA and put it at https://github.com/Arnavion/riscv . You can see a screenshot and video of the CPU in action there.
The game's campaign walks you through creating a simple 8-bit CPU and then a larger CPU similar to old ARM. But then it also has a sandbox to do whatever, and you can use whatever design you want to solve the puzzles intended for the original two CPUs.
I also made my own assembler as part of learning the ISA and put it at https://github.com/Arnavion/riscv . You can see a screenshot and video of the CPU in action there.
The game's campaign walks you through creating a simple 8-bit CPU and then a larger CPU similar to old ARM. But then it also has a sandbox to do whatever, and you can use whatever design you want to solve the puzzles intended for the original two CPUs.