In Poker if?

Question

someone bets and nobody else calls or raises does that mean the game is already over?

Answer 1

The hand is.  The person that bets get the money and the next hand is dealt.

Answer 2

The game is not over, simply the hand is over. In tournament play, the "game" is over when one person has all of the chips. If not a tournament, players may come and go as they wish at the conclusion of each hand.

Answer 3

That Hand is over.  If no one else at the table is willing to call or raises his bet then the only other option they have left is to fold to his bet.