I am looking for a word that would describe a concept or activity, such as playing a game X, that is<sup><ref>1</ref></sup> neither boring nor interesting. In other words, it should mean ‘neutral’ wrt intrestingness (~ boringness) but still comparable on the scale of intrestingness to both ‘boring’ and ‘interesting’.

An example sentence would be

*As far as I'm concerned, long-distance running is* [insert word]; *it is not boring but it's also not interesting.*

Criteria<sup><ref>2</ref></sup>

 1. Has to be unambiguous<sup><ref>3</ref></sup>, and may consist of two words at most.
 2. Has to be a single word.
 3. Should be formal in the sense that it is included in Cambridge Dictionary, or Merriam Webster, or both.
 4. Should not contain negating prefixes, such as ‘un-’.

**Does such a word exist in the English language?**

For readers' convenience, please state which criteria you believe your word suggestion has met. You may do so, *e.g.*, by adding a disclaimer at the top or bottom of your answer. Simply writing (1., 2.) is sufficient.

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<sup><ref>1</ref></sup> Assume a ternary system of intrestingness.

<sup><ref>2</ref></sup> If not all criteria can be met, you may relax the requirements from bottom to top, in the following order: 4. -> 3. -> 2. -> 1. Answers with the smallest number of relaxed criteria *in this order* will be preferred in accepting. For example, fulfilling (1., 2., 3.) is better than achieving (1., 3., 4.). Situations where a higher priority ordering fulfills fewer criteria than a lower priority vector, such as (1.) vs (3.,  4.), will be assessed on a case-by-case basis.

<sup><ref>3</ref></sup> Words such as ‘unappealing’ thus even fail criterium 1 because in a three-valued system ‘unappealing’ ~ ‘not appealing’ ~ ‘not interesting’ can be taken to mean either ‘boring’ or ‘neutral wrt intrestingness’.