Apple users were abuzz late last week as Super Mario Run hit iOS devices. However, while many gamers, both fairweather and hardcore, indulged in the ultimate of Nintendo nostalgia, investors were treading with caution.

Nintendo stock has dropped more than 16 percent since Super Mario Run hit the market, according to the Wall Street Journal. Previously, shares of the Japanese gaming company had risen more than 20 percent in the month leading up to the game’s launch. Now, industry analysts predict, Super Mario Run won’t do as well as was originally expected, due to the fees associated with gameplay.

One of the primary criticisms of the game is that it is free to download, but charges quickly crop up as users get into the swing of things. Reviewers indicate users can play for about five to 10 minutes, passing the first three levels of the game, before they are prompted to pay $9.99 to unlock other areas of Super Mario Run and continue the rest of the game.

While price details were not revealed during the game’s announcement, reports that Super Mario Run was not free soon followed. However, many users still surprised to find a paywall after several levels of the game.

This sets Super Mario Run apart from its fellow nostalgic mobile game, Pokémon Go , which has a free to play with in-app purchases structure. While users are encouraged to spend money on various game aspects to move them forward in gameplay, it is not required.

This structure helped Pokémon Go generate $100 million in revenue between July and September. The original $60 million revenue prediction for Super Mario Run has since dropped to between $12 and $15 million for first month sales, SuperData Research, CEO, Joost van Dreunen told IBTimes. Nintendo’s hopes that Super Mario Run would follow in the footsteps of Pokémon Go have quickly been dashed, Ace Research Institute analyst, Hideki Yasuda told the WSJ .

Apple announced in September, its partnership with Nintendo and its affiliate, Niantic, to exclusively launch Super Mario Run on its platform. The game is expected to launch on Android in 2017; however, major criticisms over the game’s price now cloud the impending launch.