The main difference between online and offline slots is that offline you can win more money than online if you know what to expect from a particular slot machine and are able to determine when it goes cold. Another significant difference is that if you are playing your favourite game online and clearly see that it is completely dead, you will have no choice but to leave or keep killing your balance in hopes to get the bonus game. In a real casino, you can simply jump to another machine and try the same game, but an unrelated one to your previous play.
In UK's real casinos, most slots are from IGT or Novoline. The newest IGT slot terminals look like space shuttles with different flashy features and loud noises, but they are all designed with mugs in mind, just like Pragmatic and
Nolimit City online slots. While there seems to be a lot going on, you won't notice much change in your balance.
Novomatic in my opinion are the best to play for any type of player, but all must know what they really want to achieve. For example, for a low roller that would be happy to cash out at least some £100 while playing at 0.5, i think, the best bet is to play Cash Connection games because their bonuses come pretty often. Minor and major jackpots no rarities too. But it's worth remembering that some Cash Connection games are better to play than others. If you're not sure which to play, simply hang around for a bit and look for what the majority of players do.
I find their new Cash Connection game
pretty decent. It can throw a cash bonus, a free spin bonus or both starting one after another.
Here are some screenshots from a couple of days ago.
Golden Book of Ra
This is also a new Novomatic game that many people are playing, but I can't remember its name.
While I was playing Lucky Lady, a random jackpot came in.
I think in UK's online casinos it's nearly impossible to get this combination online right now; a few years ago, I was getting it 1-2 times a month.
.. That was fun 
