Structure of the Game
OSR+ has four game modes, which the GM uses to structure the conversation. Within these game modes, you can take different types of action.
Actions & Mechanics
Note that the actions listed in each game mode do not necessarily have specific mechanics tied to them. For example, in exploration mode, there is an action called Stabilize Others that has a specific check you'd use to resolve it (a stabilize check) but there isn't a specific check for Consult the Lore: the GM chooses a mechanic that makes the most sense at the time you take action. Actions are listed to give you an idea of the sort of things you can do in the fiction, and should not be treated as a "playbook" for your character.
The Modes
Downtime
In downtime, your heroes can introspect and have intimate conversations with other heroes or NPCs.
EncounterS
In encounter mode, you can only take actions the rules-as-written prescribe and any action you can take in exploration mode (with the exception of Dungeon Crawl and Social Combat). Encounter mode encompasses moment-to-moment action, like combat.
EXPLORATION
In exploration mode, you can take any action that you imagine is possible in order to explore the environment, be it a haunted house, a secret labyrinth, or a mad scientist's laboratory.
Overworld Play
In the overworld, you can only take actions the rules-as-written prescribe. Overworld play dictates what happens in the the narrative that exists outside the point of view of your characters. It is the only game mode where you take action as a player, rather than your hero.