First things first, game bots are not illegal but can in some cases be against the terms of service of gaming sites like online casinos and online poker rooms. There is no real reason why they should be against the TOS of online casinos as blackjack bots or roulette bots really do not give the player any significant advantage over the casino, except that they will play the game for you with no errors thus minimizing your losses, and allowing you to walk away with a fair chunk of the bonus (free money) or more.
For blackjack bots they will play the perfect basic strategy of the the blackjack game the online casino that you play offers. All you would need to do is set the playing parameters of the blackjack game that you are going to play. This includes the number of decks used, the number of times you can split cards and whether you can double on any card or only face cards or aces. These rules of the game of blackjack played will determine how much of an advantage you can have from the house and the game bot will adjust play automatically to yield the most advantage. Then you just press a button and it will play for you while you relax. The one I recommend in my biobox below, I have tested and it works very well. So well it seems that the casino I played it at (intercasino) have reduced the amount of bonus you can get each month. But it is still a profitable proposition, especially as you don’t do any work to get the bonus money.
Poker bots are a bit more tricky but also very profitable. Strictly speaking you are not allowed to use them as it gives you an unfair advantage over the other players so poker rooms bans use of them. This means if you get caught, your account will likely be banned or at least suspended. It is risky but the amount of people on poker rooms that use it is quite staggering. Poker bots range from holdem or omaha calculators that only basically give you a summary of how well your hand is doing against other players to full on cheating bots that claim they can read not only your hand but that of your opponents. Bots that make those claims are definetely illegal since do be able to read other player’s hands would entail hacking and that is illegal. But other holdem bots or omaha bots and poker bots in general work just like blackjack bots and play the best strategy given the hands that you hold. There are many variations of poker bots of which I also recommend below but in essence I would never recommend you set and forget poker bots because online poker is more dynamic and varied in its play than the more rigid game of blackjack or roulette. So if you plan to get a poker bots make sure you remember not to set and forget but keep monitoring or else you might get a nasty surprise when you log back into your online poker room.