Gauntlet!

[chadtower]

So, what's the difference between the one in the Tengen casing and the one in the standard casing?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3018742867&category=3608

[CrazyImpmon]

The difference:

One had grey plastic case with gold Nintendo Seal of Approval. Other has black case and doesn't have the seal. That's all.

Tengen started out as a licensed company and they had released 3 NES games (Gauntlet, RBI Baseball, and Pac Man) but Tengen was tired of the slow development and production due to "chip shortage" and the high licensing fee, broke away from Nintendo and started making more games on their own. Nintendo did sue Tengen over the use of lockout chip but lost.

[chadtower]

Is either version particularly rarer than the other?

[SoulBlazer]

Actually, I imnagine that the licenced versions are rarer -- a check in the handy DP guide does seem to confirm that. How MUCH rarer, who knows? :)

Actually, Nintendo WON that court case aganist Tengen -- because Atari did some hanky-panky to get the information from the Patent Office under the table. A complete mulit-page write up about the whole affair is in the wonderfull "The Ultimate History of Video Games" by Kent.