The games created by NULLL are made available for free. NULLL Games is not a company and doesn't exist solely to generate profits, but there are some costs involved in creating these games and making them available. By placing ads inside the games and on the NULLL games website, most of these costs can be recuperated.
If you want to help out NULLL with its operational costs, or contribute to future plans, you can do so by using the donate button below, which will take you to the paypal site. If you prefer to use skrill, you can send any donation to firstname.lastname@example.org
In any case, when you make a donation, be sure to include the username of your account on the NULLL site. Any donation of 5$, 5 euro, or more will remove ads for your account forever, when you are visiting the NULLL site while logged in (might not apply to all older games).