This file, COLOSCAV.ZIP, was downloaded from http://www.cpcgamereviews.com/c/index7.html#colossal_adventure
or directly from ftp://ftp.nvg.ntnu.no/pub/cpc/games/adventur/text/coloscav.zip

It appears to be GERA_XXX.

The review accompanying the download link is:

Colossal Cave Adventure
(Duckworth, 1985)
Reviewed by Richard Lamond

Of all the versions of Will Crowther and Don Woods' Adventure on the CPC, this is probably the poorest. From a plot point of view, the game is top notch, following closely to the seminal template. However, where Colossal Cave Adventure lets itself down is in its dreadful response speed and presentation. The game takes a virtual ice age to respond to each of your commands, and although having no graphics doesn't hinder the gameplay, the choice to have red text superimposed on a yellow box against the CPC's regular blue background is really ugly. The game is also written entirely in unprotected BASIC. The sloppy execution would be bad enough in normal circumstances, but when you compare it to the much slicker versions released around the same time or even earlier, it makes Duckworth's interpretation seem all the poorer. 
