Hi folks! Here is one of my one weekend project that I made back in 2013.
A custom MBR (Master Boot Record) booting a snake game. Once installed on an usb flash drive it will boot instead of your system.
Start from qemu
$ qemu-system-i386 snake.img
Start from Virtualbox
Import snake.ova from virtualbox and start !!
$ sudo dd bs=512 if=snake.img of=/dev/YOUR_USB_KEY_DEVICE
Replace YOUR_USB_KEY_DEVICE by your usb device (example: sdb or sdc). Be careful if you choose the wrong device your computer might break. WARNING: This command will cause your USB device to lose any data present on it.
Booting on this USB device will not harm your computer.
Start from bochs
Tested using bochs BIOS v2.6.2 and VGABIOS v2.6.2.
$ bochs
If the bios is not found by bochs, create a dedicated configuration file and include it at runtime with
$ bochs '#include PATH/TO/YOUR/CONFIGURATION/FILE'
Note: when using git bash in windows, the path should be formatted for windows ("c:\PATH\TO\FILE") instead of an unix path ("/c/PATH/TO/FILE")