As lovely as the footage from the Sonic 2 HD alpha release looks, you're not going to want to download it once you hear what comes with it onto your computer. The fan-made remake of Sega's classic platformer contains keylogging software that records everything you type into your computer and may or may not send it off to some malicious party. It can record financial information, user names and passwords—you name it.
Sonic Retro, the community site where the project is hosted, posted the following warning: "Earlier today, I was contacted by a professional antivirus employee who was interested in whySonic 2 HD consistently popped up as a threat by multiple antivirus software programs and did some investigation. His results showed that a keylogger is part of the Sonic 2 HD software. After receiving this notification, we conducted our own independent tests and found that there is indeed a keylogging program as part of the Sonic 2 HD alpha software.
"I want to emphasize that at this time, we have found no evidence that the software has been 'phoning home' any data—only that we have found the capability exists.
"Because this vulnerability has been found, we are strongly advising that the software be removed. You will need to delete the files included with the Sonic 2 HD zip, as well as the registry keys hooked at HKEY_CURRENT_USER/Software/NakaSMK (if you are unfamiliar on how to do this, go to Start->Run.., type regedit, follow the folder path, and then delete the NakaSMK folder.)
"We will have more information on the situation as it evolves."
At this point it's unclear who attached the trojan to the software. Judging by the comments on the warning, though, there's been enough controversy surrounding the group behind the project that they're not above suspicion. Have you already downloaded the game? Did you experience any weird behavior or warning signs from your computer? Let us know in the comments or on Twitter.