What Megaways actually means at the controls
The Dog House Megaways looks like a normal six reel machine until you notice that the reels are different heights, and that they are different heights again on the next spin. That is the entire idea. Each reel independently displays a variable number of symbols on every spin, and the number of ways to win is recalculated from those heights each time the reels stop.
There is also usually a horizontal reel above the grid that adds symbols to the columns beneath it. It is easy to ignore because your eye does not naturally go there, and ignoring it means misreading half the wins you get. Make a deliberate habit of scanning the top row before you look at anything else.
Because the number of ways changes constantly, this machine is far less legible than the original Dog House. That is the trade: more chaos, more upside, and a much greater need to actually read the info panel before you start. The demo, running on virtual credits with nothing to deposit or withdraw, is the correct place to do that reading.