Ehhh.. What's meant by "message" in that quote is usually something more like an actual textual message from a developer, like "Stormbrew was here!", not a visual cue for the game itself. Easter eggs are meta, this is not.
It's also something you have to seek out -- by going to a particular place and doing a particular thing. This is just something that happens in the game, and it happens without player triggering.
The wikipedia page agrees with me on this, as far as I can tell, if you keep reading past the first sentence (which is a summary, and as with many wikipedia summaries, is incomplete and vague). This first paragraph from the software section seems rather more useful to quote:
> In computer software, Easter eggs are secret responses that occur as a result of an undocumented set of commands. The results can vary from a simple printed message or image, to a page of programmer credits or a small videogame hidden inside an otherwise serious piece of software. Videogame cheat codes are a specific type of Easter egg, in which entering a secret command will unlock special powers or new levels for the player.
It's also something you have to seek out -- by going to a particular place and doing a particular thing. This is just something that happens in the game, and it happens without player triggering.
The wikipedia page agrees with me on this, as far as I can tell, if you keep reading past the first sentence (which is a summary, and as with many wikipedia summaries, is incomplete and vague). This first paragraph from the software section seems rather more useful to quote:
> In computer software, Easter eggs are secret responses that occur as a result of an undocumented set of commands. The results can vary from a simple printed message or image, to a page of programmer credits or a small videogame hidden inside an otherwise serious piece of software. Videogame cheat codes are a specific type of Easter egg, in which entering a secret command will unlock special powers or new levels for the player.