If you are nostalgic for the days when you had a Sega Megadrive then you will love Gens which emulates the classic games console.
Gens has a number of features to enhance your playing experience such as Window mode - for playing within a small screen on your desktop or Fullscreen mode - for a genuine Sega Megadrive experience. The emulator also supports Joysticks to make your playing experience even more realistic (if you've still got one!). There's also support for Netplay and Save/Load state support meaning you can continue your gaming a later stage. However, you may find that it can't read some Sega Megadrive CD ROMS because its not compatible with all CD ROM drives. The developers advise that if when you put a Sega/Mega-Cd game in the drive and boot and you get the menu screen with tracks, this means that the Sega/Mega-Cd doesn't recognize the cd as a game. In addition, if you get a message telling you that the program is "Checking the CD" continually, it's likely that the CD's are dirty or scratched. However, don't worry as you can run games from a CD image file instead of a CD so all is not lost.
For anyone who loved their Sega Megadrive, this is a great way to roll back the years and breathe new life into your dusty game collection.