This is a slot of 5 x 3 reels where the player must pay 40 credits for 30 lines; 10 additional credits will most likely be some kind of extra fee to subsidize somehow ongoing rewards derived from the constant activation of the round of free spins, which is for me the magnet of this game.
There are also two other features that are essential part of the essence of this slot; the first is that it pays combinations formed in both directions, from left to right and right to left, which definitely increases the power of the other features and also the performance during the base game; the second is the random activation of a stacked wild reel that can happen either on reel 1 or reel 5.
The reason why which free spins are particularly exciting and profitable is that during this round of 4, 5 or 6 turns, we permanently find reels 1 and 5 turned into a pair of walls made entirely of wild symbols, additionally all “sevens” symbols can be combined between them if they form combinations of 5 of a kind, so it is virtually impossible to get out of the round of free games with empty pockets.
I would say that, on average, total earnings for each of the many rounds of free spins that I managed to trigger during my session were between 20x and 30x my total bet, which is great because this round is usually triggered with astonishing frequency, even once it happened I triggered some round just after termination of another.
I think as long as the recurrent activation of the free spins round is met, this game has a huge potential for profit; if at any time the flow of free rounds slows down, then you're in trouble.
Let me just say, briefly, “Firehouse Hounds” is a simple but interesting video slot that is highly dependent on its normally frequent activation of free spins and while the latter is met you will have in it a good chance to make a profit; therefore, I see no reason as not to suggest you give it a look.