Your analysis is correct. Although I completely agree with your post in substance, there are two minor corrections I would contribute:
First, colors cannot be "trademarked" in the conventional meaning of the word. UPS does not own a trademark over the color brown, nor does John Deere own the color green. UPS cannot prevent trucks, or even delivery trucks from being painted brown, nor can John Deere stop farm equipment from being painted green, so long as a reasonable person would not be confused by the origin of the product. What these companies do have, however, are trade dress restrictions which are also governed by the Lanham Act. Trade dress describes your product's overall appearance and packaging of a product or service. At the most liberal outset and expansive of protections, Two Pesos states that trade dress can be distinctive [and thus deserving of protection] without having to show that the trade dress has acquired secondary meaning [has itself become distinctive for other market reasons]. This is the case law as it stands today, though a huge number of critics have taken huge exceptions to this ruling. Two Pesos was reigned in by Wal-Mart v. Samara which stated that a products design is only protectable by showing of secondary meaning. In that sense, Tide cannot claim trade dress infringement by orange-bottled fabric detergent without showing that the orange bottle has acquired secondary market meaning. UPS's brown trucks and John Deere's green tractors will likely have secondary meaning, but the question does not stop at trade dress. Instead, trade dress goes to a likelihood of confusion (so does trademark, but trademark prevents literal infringement in a same category where trade dress may not). For example, If I sell you a green tractor with yellow accents, you might think it came from John Deere. If I sold you the same tractor with purple accents instead of yellow, you likely would not, and I would not have infringed on John Deere's trade dress.
The distinction is best summarized (although I still disagree with the ruling) by Louboutin v. Yves St. Laurent, where a federal appellate court ruled that monochromatic red shoes cannot be 'trademarked' but that red soles on a non-red shoe may be [again dependent upon finding of secondary meaning].
Second, there is an inherent difference between trademarks like "Apple" and "Google," "Photoshop," and that of "Memory." "Apple" and "Google" would fall under the "arbitrary" or "fanciful" categories (respectively) since "Google" is a made up word with no other meaning, and "Apple" is the use of a generic word in a completely unrelated context (computers). Continuing in order of protection, "Photoshop" would be "suggestive," since it is a unique combination of words that suggests the nature of the product [i.e. a digital workshop in which you can retouch photos]. Blu-Ray is a good example.
Memory, on the other hand, is a descriptive mark, which is the least protected and only one step above an unprotectable generic word. "Memory" is directly related to the meaning of the board game in which you must "remember" the location of the cards to match them. The only way that descriptive marks gain protection is if they have developed some secondary meaning in the marketplace. As such, Ravensburger has a much higher standard to prove that they are considered to be the source of the "Memory" game than any other "memory" game on the market. Their continued ownership of the trademark seems to evidence that they have done so.
But you are absolutely right in that Ravensburger has the trademark, and any maker of a "Memory" game is infringing on that trademark. However, the makers of these apps may file an action against Ravenburger to invalidate their trademark and preserve their app's name. So this isn't big, evil Apple beating up on the little guys. These guys are infringing, and they have the burden of proving that Ravenburger is not deserving of the "MEMORY" trademark. They just might have a better chance of invalidating the trademark than, say, Zynga, who instead must call their Scrabble-like game "Words with Friends" instead of "Scrabble" because "Scrabble" is itself a fanciful mark and thus not subject to invalidation without a showing of abandonment.