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Abiotic Factor

Microtransactions in Abiotic Factor are summarized as...

The game currently contains two DLC packs that provide extra content in the form of both cosmetics and new playable areas. When playing with multiple players, only the host of the lobby needs to own the DLC for all players to be able to access DLC locations. Cosmetic content that comes with the DLC is only available to those that own the DLC.
One of these packs, the Support's Pack, was granted for free to all players who purchased the game during the early-access period.
Similar DLC packs are expected in the future.

In their own FAQ they list the following:
Will the game have microtransactions?
Nope! If you purchased the game you have access to everything inside of it, barring a few unlockable treats via gameplay. No premium currencies or paywalled content is planned, though we do have plans for premium DLC down the line. All pricing information for extra content will be laid out clearly as we get closer to release – no surprises.
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Contains no microtransactions, but does contain some smaller scale DLC that provide extra content.
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You can invite friends to play with you even if they do not own the game and/or specific DLC content.