Virus is composed of several puzzles that you must solve separately and together to win the game. In other words, the answers you gain from one may be used to solve another.
Virus reminded me of The Machine in the artistic and stylish way each of the puzzles was designed and presented. Immersion is affected negatively, however, when a new browser window is opened up for each new puzzle. However, through an email exchange last week, Toby said he plans to merge them all into one game window sometime soon.
In Treasure Hunt, you use the clues found in a captain's log book to find the location of a mysterious treasure island. The log book is all encrypted in code and you must use whatever resources available to decipher it, which then grants you access to even more maps and clues.
Neither puzzle is easy to solve, but they are worth the while if you put the time into the effort.
Nice work Toby, keep 'em coming. =)