Slot machines are truly randomised and are regulated by governing bodies in order to make sure that the RNG (Random Number Generator) component of the slot machine is making things as fair as they should be. When playing at these casinos, you need to be making sure that they have a governing body which has audited and approved these casinos, stating that they are fair to the players and can be trusted. This should be a mandatory requirement that you should be looking for when signing up to a casino. It is recommended that the top 2 governing bodies are currently MGA (Malta Gaming Authority) and Gaming Curacao.
Casinos do not actually have input on the payout of the games. These games are made by external providers and they are the ones which set the RTP and hit rate, then these games need to be approved by governing bodies before they can be deployed on any legitimate casino. It is not in the interest for the game creators to tweak or alter the games, they are already set in a way which does favour the house, with the typical casino slot game RTP being set between 95%-97%. The slot game creators do not run the casinos so it would not be in the interest of them to not make a fair game or to tweak it specifically for certain individuals who are playing the game.
As a follow up to the question above, no. Casinos cannot choose who wins and loses, this is not something which would be allowed by any casinos governing body and would result in major if not detrimental consequences for the casino. It is absolutely not a risk which a casino would consider taking should they even have the capability to do such a thing.
There is no “best” slot game to play online, slot games come in all different shapes and sizes with some simplistic and some wacky features and themes. The “best” slot game is a term which is just subjective to you. There are certainly some games which are more popular than others, or have just become famous slots over time, however that still doesn't make them the best online slot game, this is for you to decide personally.
Also as a side note, with RNG involved, theoretically there isn't exactly a best slot game either as all of them can have moments of winning and losing.
Volatility essentially is how often the slot game will pay out, though its not exact how much on any slot game you play, some of them have different modes of volatility, in which you can set. So typically something which pays out more often, tends to pay out less sums of money and something which pays out less often tends to pay out bigger sums of money however this doesn't necessarily affect the slot games RTP as its still maybe paying out the same 96% for example, just done in different ways.
All slot games have a rough volatility which can often be looked up, not all slot games come with a feature which allows you to play and actively change and alter the slot games volatility.
There really is no secret to winning slot games, this is just the way that RNG works. You pretty much go in, select the amount of money you want to spin and then hope for the best. Some slot games come with varying things you can do, including but not limited to bonus buys and different volatility settings or even paylines, however this does not realistically change much.
There is no cheat code, this isn't a video game, this is all chance and even selecting whatever options or X amount of spins at this amount of money won't realistically change anything because at the end of the day it's all down to RNG.
No, there is no way to predict when a slot game will hit. Slot games are based on RNG, if there was a way to predict when a slot will hit then there nobody would be playing until they knew it would hit and then that would mean the game wouldn't move or be played at all as who wants to spin knowing they would lose money without the chance of winning?
There is unfortunately no way to maximise your winnings on a slot game except for the classic “quit while you're ahead”.
There are many free slot games available on a hell of a lot of casinos, as they tend to come in forms of “fun play” modes which are pretty much free trailing the slot game before you actually go and put money on it, but usually casinos will just let you do this inevitably.
There is no one most popular slot game as there are just so many and so much uncollected data from a near endless amount of online casinos. Popularity as a measure is also a bit sceptical to answer as its potentially a time based question. Obviously an older slot game will have had more players on it than a new one however a new one may have a high amount of visits over one month which could be classed as popular. Thus aside, some of the most famous if not “classic” slot games would notably be: Gonzo’s Quest, Immortal Romance and Starburst!