Around the middle of the war, rumors had reached the Zeon Dutchy that the Federation had initiated their own mobile suit program. Zeon suit development went on unconcerned until the appearance of the RX-78-2 Gundam, which laid waste to any Zeon unit that had the misfortune of crossing it. It's performance caused Mobile Suit development to be stepped up in Zeon, canceling the MS-11 Gelgoog and re-designating the number to the "Action Zaku", the first design to use beam technology.
After MS-11 was canned, Zeonic put forward the MS-14 "Gelgoog" in the shape of the YMS-14S (which would become the S-type) prototype. Thirty test units were built, the last of which was given to Zeon Newtype Ace Char Aznable while he was part of the newtype squadron. After successes in trials, the MS-14A was put into production.
The Gelgoog was the first production mobile suit in the Zeon site to use beam technology, and as such it's base armaments are a beam rifle and a twin-blade beam sword. Arguably, the basic design was even more powerful than the vaunted Federation RX-78 (Despite the Gundam's lunar titanium armament). While the Gelgoog was a formidable suit, it is a sad case of 'too little, too late'. First fielded in the defense of the Solomon fortress asteroid, the Gelgoog corps there were manned mostly by trainees and inexperienced troops. So while the RGM-79 was in fact a weaker suit, they performed better against the powerful Gelgoogs because they had better pilots.
In this rendition, the Gelgoog is a monstrous machine mounting two separate engines, and has the raw power to rip a MS-05 Zaku I in half through sheer strength alone. It is rumored it can disable other MS by hitting them, but hasn't been scientifically tested.
Pardon the older rendition of the MS-06 in the back. No effort to fix it...