Even if the obvious does not need to be stated, exchanging game keys for free plays is still very convenient.

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When buying games, consider
DRM-free platforms/portals:

gog.com

itch.io

groupees.com

Fireflower Games

humblebundle.com/store (or don't)

Show Me The Games (collects dev direct distribution links)

Bonus Links:

Steam Gifts community key exchange

SE Steam group

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