ah ha! I am in my element.
A pub 'fruit machine' is nothing like slots you have in the states.
Firstly the jackpot is set to a maximum of £70 ($100) but some are still £35 or £15 some seaside resorts have £5 too.
I know what your thinking, the jackpot is pretty stingy, but it can often repeat multiple times, some up to 3 or 4 times.
Next the payout is an awful 78-98% usually around 80%. But the machines are designed for entertainment rather than hardcore gambling. There are ways to constantly win, but I will come on to those later. The % is actively maintained by the machine, and each spin pre-determined the 'choices' it offers you have little or no effect on your result.
The machine has usual line wins, like three cherries for £1 or three bells for £70.
Wins can be gambled up to the jackpot, by going higher or lower on numbers 1-12. This gamble is not fair, and you are usually wrong when you choose higher than a 2 or lower than an 11. You can collect your win, or exchange it for the feature (see below)
You occasionally get the option to 'hold' any of the three reels (1,2 or 3) if you like the symbol on it.
Or you get the option to 'nudge' the reel down one space (or up to 4) if you like the symbol above it, these nudges can be shared out amongst the reels as you see fit, you usually know how many nudges you have, but mystery nudges are known.
There are little 'cheats' that are programmed in, so after using your nudges and you dont get a win, if the machine offers you a chance to hold the symbols, simply press spin to get a guaranteed win.
The feature board is usually something like a snakes and ladders board on the top section of the machine, you start at the bottom and work your way up to the jackpot, passing ? spaces along the way that could (nearly always) kill you. You roll the dice and get awarded cash and features along the way. The board is usually cleverly worked out so that you can always land on a ? space no matter where you are on the board. So if your getting greedy the game can be over anytime the machine wants it to be.
Most modern machines have an 'invincible' or red mode when the name of the machine turns red instead of the usual yellow colour, no matter what you a jackpot is imminent if you know how to play them. The machines go hot and cold. And unlike vegas slots, a machine that has just been hit for the jackpot 3 times, is now very unlikely to pay again for about a week. The reverse is also true, a machine that has not paid out is more likely to pay out now. You can usually gauge the happiness of the machine within the first few pounds, and decide if its worth pushing. Some people like to make the machine happy by refusing all wins, and pushing the machine over the edge to get the jackpot.
The machine tracks the money in and money out, and the actual % percentage. The difference is called drift. If the drift is say +£54.00 the machine has more money than it should, and will be looking to dump money soon. but if the number is negative it will be somewhat tight. The % is known to drift wildly, but always gets back to the target. Some modern machines build up a reserve bank that can be paid out in one lump, such as a triple jackpot repeat.