Other than forms of gambling specifically authorized by the State, anything else constitutes illegal gambling and is a Class B Misdemeanor for players. As cited on our Restrictions Page:
945.02 Gambling. Whoever does any of the following is guilty of a Class B misdemeanor:
(1) Makes a bet; or
(2) Enters or remains in a gambling place with intent to make a bet, to participate in a lottery, or to play a gambling machine; or
(3) Conducts a lottery, or with intent to conduct a lottery, possesses facilities to do so.

One unusual aspect of the cde is that it is just as bad to conduct your own lottery as it is to make an unlawful bet! Usually laws tend to be less harsh when it comes to mere players and more stringent when it comes to operators.
For other unlawful forms of gambling in the state, one could be charged with a Class 1 Felony if acting as an operator.
Despite our best research efforts...
...we could find no instance of a player ever being arrested or prosecuted for gambling online. Because of that, the majority of online casinos that offer their services in the United States at all, probably all of them, accept players from Wisconsin.
Other than forms of gambling specifically authorized by the State, anything else constitutes illegal gambling and is a Class B Misdemeanor for players. As cited on our Restrictions Page : 945.02 Gambling. Whoever does any of the following is guilty of a Class B misdemeanor: (1) Makes a bet; or (2) Enters or remains in a gambling place with intent to make a bet, to participate in a lottery, or to play a gambling machine; or (3) Conducts a lottery, or with intent to conduct a lottery, possesses...