roulette

let's get one thing straight right away - one cannot beat roulette [or any other casino game] in the long run.  no matter what your system - be it one of the various martingales, ascot, labouchere, whatever - you are just putting off the inevitable, i.e. the loss of all your money.

however, roulette can be beaten regularly if you are patient - and until you are thrown out of the casino - because it depends upon mechanics, the wheel, and mechanics are subject to failure.

in order for the ball to drop in truly random fashion the wheel must be perfectly balanced.  if out of balance a bias can be discovered and plays can be made which take advantage of that bias.  all one needs to do is chart 25 or so spins, recording them as they fall in the order the numbers are slotted on the wheel and if a bias appears play the block of numbers - say five - with a progressive series of bets - say five [1,2,3,5,8?] - going up with each loss and going back to the start with each win.

i know this will work - i have used the "system" several times at various casinos.  interestingly, the americans are less likely to challenge one with a pad and paper [confidence in their maintenance?] while the argentinians threatened me with jail the minute i started to write.