[luplex]

continuing off the tangent, "party" is a noun, not an adjective. In a construction "party politics", it functions _like_ an adjective, but it remains a noun.

Similarly, "computer" in "computer games" is a noun that modifies the meaning of the following noun. Modifying nouns like this always are in singular.

[cmpb]

Specifically this type of modifier is called a "noun adjunct"

[deaux]

Great point, thanks for the correction.

[milkshakes]

what about "sports betting"

[judahmeek]

adverbial noun