Most people would say that Protector LE is the Holy Grail of the Vectrex. Some would say that VeCaves is the rarest game ever made for it. Here's a number of games you might not have even know existed. These are the most elite carts and releases for the Vectrex.

Zantis : 99 Ways to Die
Zantis only had one special edition but 10 carts were available in its release. It included a special key chain. As part of this release's exclusive gameplay, the player was supplied with 99 ships.
War of the World : Time Rift
So far only this special release has been made for George Pelonis' most recent game. 10 cartridges featured special labels packaged in side of an art box similar to those featured in the special releases of Continuum. Included was a wrist watch which was engraved with the Mothership. To reward the buyer for their purchase, the game also featured an added hyperspace.
Royal 21 : Christmas
1 of 3 special releases for Royal 21, this version only had 5 carts to it. Released within red reproduction cartridge shell, they included unique labeling and manuals. As features to the gameplay, it included a Christmas intro as well as an exclusive Santa joker.
Sundance : Dark of the Sun
Only 3 cartridges exists of this special release of Sundance. In addition to its special art box, it featured unique labeling and a reproduction red cartridge casing. 2 patches were included. Gameplay featured variable difficulty settings involving invisible grids and disappearing suns.
Sectis : Master Edition
Only 1 Master Edition was created, numbered 000. It included a Sectis T-shirt just as the first 100 copies of the game sold were and just as they were housed in clear cases, this was the only one housed in a red reproduction casing. Also included were maps for every level and an exclusive game feature allowing the player to start from any level.
Vectrexians Deluxe
Available only to the winner of the first person to finish the standard Vectrexians, WizdawG became that lucky person. Visually, it is differentiated by its red reproduction cart casing. Its unique game features included many options such as Minestorm mines replacing the Vectrexians, alternate background and playable closing animation.
Royal 21 : Boston
Only 1 cartridge was made of this version of Royal 21 named in honor of the Mr Boston version of Clean Sweep. In addition to its unique labeling it also feature a light up cartridge case.
Vector 21 : Omega
Another exclusive version of Vector 21 limited to only 1 cart. Unique labeling and gameplay which featured more jokers and a special Psycho 7 mode.
Sundance : Matrix
The most unique version of all of George Pelonis' games. This version was limited to only 1 release and included a special controller that works with its exclusive gameplay. Each button corresponds to one of the 9 sections of the grid and was created to mimic the arcade version more accurately.
Spike's Circus : Eurocon Charity Version
Limted to only 1, this was a special version of the game put together by Alex Nicholson for auction at Eurocon 2005. This version features all the levels already unlocked, and included a Spike's Circus engraved dogtag by Richard Hutchinson.
 
Also, while some people might consider Joust and Solar Wars Preview in the same vein, I'd consider them prototypes.
 
 
I'd like to thank everyone who made this page possible - Mayhem, Rapetou33 and George Pelonis himself.
Sector-X : Hell's Fury
Only 3 copies of this special edition were made over the original, probably due to the supply demand factor in needing the 3D Imager. It includes an additional sector not used in the original game due to incompatibility with some imager units.
I, Cyborg X
One of George Pelonis' first special releases came as 10 unique carts. In addition to unique labeling and built in serialized Roman numeral, this version featured a level selection option and a unique mohawk character.
 
Continuum : The Infernal Tetramorph
Continuum : The 7 Pillars of Purgatory
Continuum : Time Warp
Three limited edition box sets were sold 10 per separate series. Each game came packaged in a special art box and included items themed toward its specific edition. The Infernal Tetramorph (orange box) included nightlights; The 7 Pillars of Purgatory (blue box) came with a handkerchief; and Time Warp (lemon box) included a digital watch.
Vec Sports Boxing (original 13)
Manu Parssinen handmade 13 original GCE style boxed versions of Vec Sports Boxing, complete with homemade overlay. These were the only versions made with cardboard boxes and overlays. Later releases would be sold in VHS clamshells or plastic keepsake boxes. They were made from florescent green posterboard which Manu happen to have.
Debris Exclusive Edition/Debris Revisited VIP Edition
This is a more well known release than others included on this list. Each came numbered as part of a 20 cart set. While the unlimited came as a slim or lite pcb only, the limited edition version of Debris came in a reproduction Vectrex cartidge shell. In addition, these were the only version which included cardboard boxes and full color overlays. While a lot of work went in to adding to the packaging for these releases, the game itself remains unchanged.
Vector 21 : Fistful of Wildcards
One of George Pelonis' more prolific releases. 21 carts were released in this version, each labeled uniquely different from the standard release. To aid in gameplay they also included jokers dealt with every deck.
Royal 21 : Vegas
This edition of Royal 21 was named after the 2010 Classic Gaming Expo which was held in Las Vegas. As part of its unique packaging, it was housed in a clear reproduction cartridge shell. It also featured an exclusive joker, Jonny Vegas. Only 21 carts were part of this release.
Star Sling Limited Edition
25 numbered sets of this version were made, only 20 offered to the public. These were the only versions of Star Sling which came with a GCE style box.
I, Cyborg : Omega
Another one of George Pelonis' first exclusive offerings. This is the pinnacle of I, Cyborgs special editions. Limited to only one, offered only through ebay auction, the original owners name and bid was included within the program. In addition to its special labeling, it also included an I, Cyborg Collectors booklet. The game itself included an exclusive fedora character as well as a stage selection screen.
War of the Robots : CGE2K3
Named in honor of the 2003 Classic Gaming Expo where WOTR debuted, only 1 was made. It included a Fury mode and special menu screen in addition to its special instruction manual and special label.
War of the Robots : Omega
This is the ultimate version of WOTR. Only 1 cart exits. Above and beyond the WOTR : CGE2K3 cart's features, it included a code mode in addition to its Fury mode, special menu screen and exclusive instruction manual and special label.