Learn Turkish: Mekân uygun olmazsa, katılımcılar gelmeyecek. - If the venue is not suitable, the participants will not come.

It uses the negative aorist conditional taught in this lesson. The base is olmak (to be or become). The negative aorist form is olmaz (it does not / it will not be). We then add the conditional suffix -sa (if). Together, olmazsa means 'if it is not'.

Why is the future tense used in gelmeyecek but the aorist used in olmazsa?

In 'if' sentences like this, Turkish usually uses the aorist tense for the condition (olmazsa) to express a general possibility. The result part uses the future tense (gelmeyecek) because it describes the specific action that will or will not happen as a consequence.

How is the word katılımcılar (participants) built?

It comes from the verb katılmak (to join or participate). The suffix -(ı)mcı turns it into a noun for a person doing that action, giving us katılımcı (participant). Finally, -lar makes it plural.

The subject katılımcılar is plural, so why doesn't the verb gelmeyecek have a plural suffix?

In Turkish, when a plural subject (especially humans) is explicitly stated in the sentence, the verb does not strictly need a plural suffix. You could say gelmeyecekler, but leaving it as gelmeyecek is completely correct and very common.