While I personally do like steam as a platform, I think that it is important to keep information related to it in order to make sure that potential buyers are aware of issues they might have when using the platform.

If a game gets removed from the Steam Store

Once you have purchased a game from the steam store, it is yours forever. Even if it gets removed from being purchased from the storefront you can re-download it from steam to add to your PC, Steam Deck, Steam Machine, etc.

Example

Spec Ops The Line was removed from Steam around late 2023, due to music licensing issues.

Spec Ops: The Line Steam Store Page 

However, players that have purchased the game before the removal from steam are able to download it onto their PC through Steam.

Downloading Spec Ops: The Line 

Once you have downloaded the game, you can play it whenever you want.

Spec Ops The Line: Available To Play 

Requirements For Steam

Requires the Steam Platform to Play Games on Steam 

If you purchase a game through the steam storefront, through either steam platform or through the steam online store, you are required to have Steam installed on your PC in order to play games on their platform.

Can play games offline once a user initially signs in through their PC, Steam Deck, or Steam Machine.

Once you sign-in you can play games offline if you lose internet connection or click Go Offline in the main menu. 

Requires Up To Date Version of Windows OS 

If the user intends to buy a game on Steam to play on their Windows PC, they are required to have at least Windows 10 to play games using the Steam platform. Additionally, steam will no longer be supported on 32-bit Windows Operating Systems. (Valve, 2026)

Sources