Book of Oil - the black gold. That's where oil is also known as. This black stuff has made cunning businessmen millionaires, sometimes even billionaires. You too can try to make a fortune with the online slot Book of Oil from Endorphina. With this slot you take on the role of a real big fat Texan oil tycoon, who, complete with a big, expensive car and a big cigar, is looking for oil.
And just like in real life, this Book of Oil is a matter of two extremes. Or you know where to find oil and then you can really earn a lot of money. Or you always drill in the wrong place and then your balance can go down sharply.
So make sure you start with enough starting balance when you play this Book of Oil with real money. You can swim in the oil and the money, but sometimes you also have to endure a long period of drought.
Book of Oil has 5 reels with 3 rows of symbols. As with so many older titles from Nextgen, the number of paylines is variable. Choose between a minimum of 1 and a maximum of 10 paylines. This slot already has a very high variance, and if you play with less than 10 paylines, the variance only gets higher.
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The minimum bet is 0.01 euros per spin and the maximum bet is 250 euros per spin. The theoretical payout percentage is 95.66% - Unfortunately, Nextgen's slots are not known for high payout percentages.
The symbols consist of a mix of premium symbols that have everything to do with the (successful) drilling for oil and the well-known card symbols. The premium symbols consist of a derrick worker, a big expensive car, a graph with winnings, and a suitcase with money.
5 employees on an active payline pay out the sweet sum of 5,000 coins. The other premium symbols are worth between 250 and 1,000 coins.
The card symbols 9, 10, J, Q, K, and A pay out between 100 and 200 coins with a 5-of-a-kind on an active payline.
The Upwild Feature is the only bonus feature in the game. This feature is activated as soon as 1 or more scattered bonus symbols (the oil tycoon) appear on reels 2, 3, or 4.
You now get 3 free respins, with the tower of wilds getting one step higher with every spin. It is possible to win the extra respins when a new bonus symbol appears on the other reels. This is of course an ideal scenario - the wilds that were already there remain active and new wilds are added.
Can you land a scatter symbol on each of the 3 middle reels? Then you have 3 reels of stacked wilds with big payouts on every respin. This can result in huge payouts, especially if you manage to spin the highest symbols on the first reel.
Book of Oil is not the best release from Nextgen. There is only one bonus feature and then it quickly becomes a bit monotonous. You can win big during this bonus feature, but we clearly miss some tension between those rare moments.
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Graphically, Book of Oil is not a high-flyer, to say the least - the symbols are somewhat uninspired and the logo is even very blocky. As if the pixels ran out the moment this slot was made.