There are four mode for you to play, lying in Realistic: All traits are available. Takes longer to play than casual. More in depth strategy than casual; Relaxed: Not all traits are available. Games are much shorter than realistic. Less in depth than realistic. Select a disease class; Virus: Fastest evolution. Most affected by environment; Bacteria: Medium evolution. Normally affected by environment. Bonus to drug resistance; Parasite: Slowest evolution. Least affected by environment. Low visibility Bonus to infectivity. Pandemic 2 is a puzzle game, Just select a play mode, available on www.flash-games.net, for totally free and your spare time relaxing and entertainment. Good Luck!