With all forms of playtesting it is not unusual for participants to be required to sign a non-disclosure agreement, in order to protect the game designer's copyrights.
Playtesting should not be confused with quality assurance (QA) testing, in which professional testers look for and report specific software bugs to be fixed by the development team.
[4] Mojang continues to make use of playtesting with Minecraft through weekly development releases, allowing players to experiment with unfinished additions to the game and provide feedback on them.
StarCraft II: Heart of the Swarm was tested in this manner; its playtest only included the multiplayer portion of the game, while the single-player campaign was not revealed.
[5] Heart of the Swarm is also an example of a playtest where average players are not being considered for entry; the initial wave of testers are only being selected from the ranks of professional SCII gamers and from the media.
The open-source video game engine remake OpenRA, which recreates the early Command & Conquer games, publishes playtests to the public during the release process so that a broader range of testers can verify that new features don't introduce critical errors such as desync problems in the lockstep protocol and unwanted side effects on the gameplay can be balanced out prior to the next stable release.
[7] Valve does not often make use of open playtesting, in keeping with the company's tradition of tightly controlling what information they release to the public.
However, both Dota 2 and Counter-Strike: Global Offensive were openly playtested, with beta invites being distributed to (and in some cases by) volunteers.
WotC focused heavily on the results of this testing owing to the mixed reactions that the 4th edition rules received,[13] showcasing another advantage of playtesting: helping to ensure that the final product will be a commercial success.
[17] Updates made to the rules are released in PDF format on their website, but there is no word on whether playtesters will get a copy of the actual final draft.
[21] Steve Jackson Games uses Munchkin players from the area around their offices to test new cards and expansions, as well as distributing playtest packages at conventions.
There are ways to prevent this; for example, requiring all players to log-on to the game's servers before it will launch, or implementing other forms of DRM.
This is a major risk for companies wishing to preserve secrecy, particularly in nations where there are no way to prevent leaks from occurring.