Detail #8: A gender-like thing but with verbs instead

A language where there are three or so classes of verbs. These classes differ in

• what affixes they take to mark different things
• what they mark (e.g. class I marks tense-aspect but no mood, class II marks tense, aspect and mood, but has a less fine-grained tense-aspect system, and class III marks tense, and every verb in it has inherent aspect that cannot be changed morphologically)
• details in the congruence system (class I has gender, person, number agreement for the subject; class II has no agreement, class III has person, number and gender agreement for subject, as well as a really minimal object-related agreement detail, as well as volition marking by means of reduced agreement)

They do not differ by 

• meaning - there's no set of meanings that unite all verbs in one of the class or exclude verbs from some class; auxiliaries can be found in all three. With these exceptions: all verbs of movement are class I verbs, all verbs of possession, exchange of possession and agreements and contracts are in class III.
• intensity, whether they are kinetic or not, transitivity, number of arguments in general, etc.

However, the classes also differ in some other ways:

• subject and object case; class II is somewhat ergative in behavior. Coordinations using nominative and/or accusative is permissible, though, for all classes.
• certain derivative affixes assign a derived verb to a specific class
• infinitives are marked for case according to what the auxiliary's class calls for

Several verbs can be finite in a clause, and which subjects and objects belong to which verb can be distinguished by case (as well as proximity to verbs, if ambiguity has to be counteracted by phrasing). The case distinctions are fewer in the plural than the singular, so this works best with singular subjects.