Unicorn Engine VS FEX

OFRAK Tetris is a project I started at work about two weeks ago. It's a web-based game that works on desktop and mobile. I made it for my company to bring to events like DEF CON, and to promote our binary analysis and patching framework called OFRAK.

In the game, 32-bit, little-endian ARM assembly instructions fall, and you can modify the operands before executing them on a CPU emulator. There are two segments mapped – one for instructions, and one for data (though both have read, write, and execute permissions). Your score is a four byte signed integer stored at the virtual address pointed to by the R12 register, and the goal is to use the instructions that fall to make the score value in memory as high as possible. When it's game over, you can download your game as an ELF to relive the glory in GDB on your favorite ARM device.

The CPU emulator is a version of Unicorn (https://www.unicorn-engine.org/) that has been cross-compiled to WebAssembly (https://alexaltea.github.io/unicorn.js/), so everything on the page runs in the browser without the need for any complicated infrastructure on the back end.

Since I've only been working on this for a short period of time leading up to its debut at DEF CON, there are still many more features I'd eventually like to implement. These include adding support for other ISAs besides ARM, adding an instruction reference manual, and lots of little cleanups, bug fixes, and adjustments.

My highest score is 509,644,979, but my average is about 131,378.

I look forward to feedback, bug reports, feature requests, and strategy discussions!

Entails hundreds of hours of single-stepping through that opcode in Linux kernel using an indirect operand pointing toward its own opcode (self-modifying code).

Even the extraordinaire Fabrice Bellard (author of QEMU) admitted that it is broke and did a total rewrite, which fixed tons of other issues.

https://github.com/unicorn-engine/unicorn/issues/364

Macdu (Vita3K dev) also stated that this game is CPU bound so they used a CPU emulator known as unicorn2 , this is also the reason for the slow speed

This is how I found out a snippet of assembly code that can actually distinguished between a KVM hypervisor and most of today’s emulator.

https://github.com/unicorn-engine/unicorn/issues/364

"A fast usermode x86 and x86-64 emulator for Arm64"

Could try this https://github.com/FEX-Emu/FEX + wine/proton. But as always keep in mind that playing on non-supported platforms can lead to bans in future (never happened but who knows).

It's explained in the video, it uses https://github.com/FEX-Emu/FEX

Steam is also funding an x86 tn ARM game emulator, which opens up the potential for it working on Android.

Valve is funding developers working on an x86-to-ARM layer, FEX. I'm assuming that the eventual end goal would be to run Steam on Android, one of the FEX developers was commenting on trying to get FEX to work on an S8 Tab Ultra.

Valve is also funding another translation layer, from x86 to ARM (see FEX).

Additionally, game emulation won't be optimal until someone fixes this issue from FEX-Emu, which will allow that emulator to run on Apple Silicon. QEMU-user is currently your best option though it is dead slow. Box64 is currently pretty capable, however, it will not be able to run any 32-bit libraries (which even modern games ship a few of).