The answer to "Can casinos change RTP?" starts with the random number generator, a piece of code that produces numbers with no pattern a player could follow. Every reel spin, dealt card and wheel result in a software game comes from such a generator, and the result is settled the instant a stake is placed. Everything shown afterwards is presentation. What makes the generator trustworthy is the testing around it, which a player can trace through a lab report and a laboratory seal.
A random number generator in a casino game runs continuously, producing thousands of numbers every second whether anyone is playing or not. When a stake is placed, the game takes the current number and maps it onto an outcome: a reel position, a card from a virtual deck or a pocket on a wheel. Because the generator never pauses, the timing of a click cannot be used to aim for a result. Stopping the reels early changes only how quickly the outcome reaches the screen.
Seals from testing laboratories often sit in the footer of a casino site, and not all of them are genuine. A real seal links to a page on the laboratory's own domain that names the operator, the games covered and the period of validity. An image that links nowhere, or to a page on the casino's own site, proves nothing. The lab report itself lists exactly which games were tested, and that list can be much shorter than the lobby.
Common questions
Are staged near misses allowed on slots?
Most certification standards limit how far a game may stage near misses beyond what its maths produces naturally, and an almost win says nothing about the next spin.
Which statistical tests does a game generator face?
Laboratories run tests on millions of outputs to check that every number appears as often as chance predicts and that no sequence repeats in a usable way.
How can a player tell a genuine laboratory seal?
A real seal links to a page on the laboratory's own domain naming the operator, the games covered and the validity period; an image linking nowhere proves nothing.
Why does the date of the last audit matter?
The date on the laboratory document shows how recent the latest check is; retests follow every game update, and many licences also require periodic audits of the whole platform.
Where is a game's random number generator documented?
In the certificate or lab report the testing laboratory issues for the game, which names the generator examined and the exact build that passed.