The game you describe is a textbook example of one relying on working memory.
The game you describe is an example of one that taxes working memory. Working memory can be conceptualized as (Chai et al., 2018):
a short-term storage component with a capacity limit that is heavily
dependent on attention and other central executive processes that make
use of stored information or that interact with long-term memory.
Short term memory being (Cowen, 2009):
[F]aculties of the human mind that can hold a limited amount of information in a very accessible state temporarily.
The difference between working memory and short-term memory is confusing, and Cowen (2009) continues by disambiguating working memory and short term memory:
[W]orking memory includes short-term memory and other processing mechanisms that help to make use of short-term memory.
However, Cowen (2009) points to another definition that is:
the attention-related aspects of short-term memory. This, however, is not so much a debate about substance, but rather a slightly confusing discrepancy in the usage of terms.
Interestingly, when you look up the Wiki page on memory span, which describes the digit span test, a textbook example of a working-memory test, you can see that they also use the terms short-term memory and working memory interchangeably. So I reckon the exact differences between the two are indeed not always clear.
Now long-term memory is another matter altogether, and is, according to the current concepts about memory, not needed for your game, other than to associate and give meaning to the items added (remembering the attributes in the suitcase in a foreign language unbeknownst to you would certainly complicate matters!). Long-term memory being
a vast store of knowledge and a record of prior events.
The difference with short-term storage is that it has a longer decay time and a larger capacity. However, the exact differences remain a matter of debate (Cowen, 2009).
Regardless the exact differences, conceptually, the game relies on working memory.
- Chai et al., Front Psychol (2018), 27
- Cowen, Prog Brain Res (2008); 169: 323-38.