KEGS Apple IIGS emulation for Linux by Chris November 4, 2008 

KEGS was written by Kent Dickey. (Kent's Emulated GS) and is regarded as one of the best Apple IIGS emulators of all time. KEGS has been ported to several operating systems and even includes a SDL.

Excerpts from the readme:

* Supports all Apple IIgs graphics modes
* Plays all Apple IIgs sound accurately
* Supports serial port emulation through TCP/IP connections
* ROMs and GS/OS are not provided with installer (still under copyright)

Features

* Default emulation of an 8MB Apple IIGS which may be changed from the Configuration Panel
* Fast 65816 emulation; runs about 80Mhz on a Pentium 4 1.7 or Mac G4 1Ghz
* 16-bit stereo sound at 48Khz (44100 on a Mac)
* Mouse and Joystick support
* Emulated battery RAM remembers control panel settings
* Emulated serial port; modem emulation functions
* Super accurate: even the built-in ROM self tests pass (must be in 2.8Mhz mode and you must set the Configuration Panel entry "Enable Text Page 2 shadow" to "Disabled on ROM 01" for ROM 01)
* KEGS supports very accurate classic Apple II sound (clicking of the speaker using $C030)
* DO NOT RUN KEGS AS ROOT. It is not designed for this and it's almost certain that problems will ensue.

KEGS supports running at four speeds: 1MHz, 2.8Mhz, 8.0Mhz, and Unlimited. Many games will be unplayable at the unlimited setting. Pressing the middle mouse button cycles between these modes. The 1MHz and 2.8MHz speeds force KEGS to run at exactly those speeds, providing accurate reproduction of a real Apple IIgs.