Jaguar 2 was Atari's next video-game console.  In development from 1992 to the end of 1995, the Jaguar 2 was codenamed "Midsummer", and as the Atari Technical Reference Manual (TRM) explains:

"Midsummer is based around a pair of custom chips, called Oberon and Puck, which are primarily intended to be the heart of a mega high-performance computer for games and leisure. Oberon and Puck replace Tom and Jerry from the original Jaguar system.  Oberon is the King of the fairies and Puck is Robin Goodfellow, his side-kick, from “A Midsummer Night’s Dream” by William Shakespeare."

According to the TRM "Midsummer is an evolutionary development of Jaguar to give significant performance gains for 3D games.  It offers greatly improved performance for a small increase in system cost. It is intended to be software compatible with Jaguar and so will run the existing library of games. The following areas of the system have substantially improved performance:
                                 · polygon rendering speed
                                 · texture mapped polygons
                                 · computational ability
                                 · audio synthesis

Midsummer is intended to be easy to program in a high-level language. It has an additional RISC processor, the RCPU, with an instruction cache to improve the performance of C programs."

Though a final design was never reached, initial prototypes were assembled and Beta development boards known as Cobweb were being shipped to developers from August 1995, yielding the following information... (The Cobweb board is a prototype development board for Midsummer which has the Oberon b-test ASIC from Midsummer and the Jerry ASIC from Jaguar One. This system is intended to allow some software development to start before the availability of Puck. The Oberon b-test ASIC is not the final production version of Oberon, and is both slower and buggier then the production silicon.)

Block diagram note: This diagram summarises the system architecture of Midsummer. It does not show the peripheral connections, or the 68000, which is still present only for compatibility reasons and to boot the system on this bus. The RCPU, GPU and DSP are all based on the same Jaguar RISC architecture. All three processors are 32-bit RISC, executing close to one instruction per clock cycle. They are tuned for graphics and audio
processing; and offer single cycle multiply operations as well as normal RISC functions.

The RCPU is new for Midsummer, and has been specifically tuned for running C code. It is intended to act as the CPU of the system, and is the geometry engine for 3D graphics.

We don't really know how far Jaguar 2 was to completion.  It is apparent however that some key developers were provided with Cobweb developer boards and hardware reference material (at least to revision 6 of the TRM).  The Atari Museum has been able to power-up a Cobweb board which was fully functional, and it ran existing games which at least proves it was fully backward compatible.  If any specific Cobweb/Midsummer code was written or developer demonstrations completed, we just don't know at this time.  If you have any further information about the Jaguar 2, please contact AEX.