Docs

"Completing the game"

Story-type and unmissable achievements are flagged as such in the context of a normal playthrough to complete the game.

However 'completing the game' can mean many different things depending on the type of game. In many cases there is an obvious campaign or story; so 'completing the game' means getting to the end of that. In other cases, e.g. for sandbox or MMO games, there may not be a story/campaign per se. In these cases, the game guide should describe what 'completing the game' means.

Note that completion in this context does not imply having done everything nor experienced all content; end-game content may validly come after 'completion'.

For example, Sea of Thieves is an online multiplayer pirate game. There are stories (the Tall Tales), but they are very optional. 'Completing the game' is defined as reaching Pirate Legend status.

Achievement flags

Kind

Story: Achieved through progressing the main campaign/store (see above). Many Story achievements are unmissable, but some may be optional, missable or mutually-exclusive based on story choices.

Grind: Requires the completion of multiple similar tasks (e.g. "kill 500 enemies"). Progress typically cannot be reset/rewound, so achieving the goal is a case of grinding out the activities throughout play.

Objective: Requires the completion of a singular objective; e.g. completing a quest, reaching a location, etc.

Note that some grind-like achievements belong as objectives if progress toward them can be reset through gameplay; e.g. Forza Motorsport's "Safety Superstar" achievement which requires the completion of 10 consecutive multiplayer races with an S-class safety rating. The 'consecutive' obligation, and the reset of progress if your safety rating drops below 'S' make this essentially an Objective rather than a Grind.

All the things: Collectibles, and other kinds of "do every kind of X" type achievements such as "craft every type of weapon" or "discover every fast travel point".

Missable

Missable: Can only be achieved in a certain part of the game, and not fulfilling the requirements will mean you can no longer unlock it without replaying the game or loading old saves.

Soft-missable: Can only be achieved in a certain part of the game, and is missed then some replay is needed to unlock (e.g. replaying a mission), but without needing to save-scum, chapter-select or restart the game.

Unmissable: Cannot be missed as part of natural toward completing the game.

Optional: Can be achieved at any point through the game, up until game completion. Note that whether an achievement can still be unlocked after completing the game is separate; the games's overall/roadmap section should describe any post-completion limitations.

Mutually exclusive: Cannot be achieved at the same time as one or other achievements. I.e. you'll have to make a choice, and whichever outcome you don't choose, those achievement(s) become missable.

Multiplayer

Whether an achievement needs other players to be able to unlock. This can be an important flag as multiplayer achievements may become hard (or impossible!) to unlock for older games with few remaining players - or where the developers have turned off online services.

Games that are purely single-player-only or multi-player-only will not display this flag; as all achievements would have the same value.

Anywhere: Can be unlocked in single and/or multi-player modes.

Single-player: In offline/single-player mode, no interaction with other players required.

Multi-player: Requires an online multiplayer mode, and/or the online synchronous interaction with other players (e.g. an Invasion mode).

Glitched

No known glitches: No problems are known. Achieve away!

Glitched: Known to be problematic and not unlocking - either for some people or for everybody. This is due to a game bug, and so there should be hope that a future patch will resolve the glitchiness.

Previously glitched: Was glitched in the past, but has been fixed by a subsequent game patch.

Unobtainable: The game has changed, via a patch, such that the achievement is deliberately no longer achievable - e.g. the removal of Arena mode in Sea of Thieves resulted in lots of Arena-related achievements that are no longer obtainable. Unobtainable achievements typically will never be obtainable in the future.