How better could I define the game?
1. A two-player game played with (upon) the sum of the figures shown by the players' fingers, in the way that if it's even, the one who has chosen 'evens' is the victor or otherwise.
2. A two-player game played with (upon) the sum of the figures shown by the players' fingers, in the way that, depending on its being even or odd, the one who has chosen 'evens' or 'odds' is the victor. Â Â Â Â Â Â Â Â Rafee
Both sound pretty complex.
This one has a simplified style, a naturally flowing structure, and good uses of key phrases: in which, two players, the object is, opponent.
tic-tac-toe - a game in which two players alternately put crosses and circles in one of the compartments of a square grid of nine spaces; the object is to get a row of three crosses or three circles before the opponent does
I've never played that game, but it sounds a lot like "Rock Scissors Paper." So assuming I understand your intent, this is how I'd write the rules:
Odds and Evens
This is a two player game involving only one of each player's hands. One player is designated as ODD, the other is designated as EVEN. Play commences with both players secretly deciding how many fingers they will display. Then, at the moment of play, both players simultaneously display any number of fingers (1-5). If the total is ODD, the ODD player wins. If the total is EVEN, the EVEN player wins.
Your description was confusing, but I'm assuming this is what you meant. The simultaneous display I refer to would be similar to Rock Scissors Paper. For example, the players move their closed fists up and down three times while audibly counting "One, two, three." When they get to "three," both players display however many fingers they've decided to use. The total determines the winner.
I do not address how the ODD and EVEN designations are assigned. Maybe that could be done using Rock Scissors Paper.  🙂
The odds of a given player winning are, of course, 50%. So why not just flip a coin? Much easier.
A most elegantly simple and fair and nerve-wracking real-life mind game is when a pair of business partners decide to part ways, but each wanting to stay as sole owner of the business: each person secretly writes down his own bid amount to buy off the other. This calls into play how shrewd a person is at mind reading, and how willing or desperate.
You all have gotten it right, but I wanted to know whether my sentences really convey what you've gotten. You know what I mean!
(They goed to school. You get the meaning, but the 'appearance' of the sentence does not convey it. It's wrong.)