Metal Slug 3
Released in June 2000 Neo-Geo, Metal Slug 3 is considered the best and hardest Metal Slug by most fans. Introducing multiple paths, interesting new slugs (an elephant that can breath fire, anyone?), and more absurd enemies (zombies and mutant plants), Metal Slug 3 brought new additions to the Metal Slug series while still emphasizing destructive shooting coupled with explosions. Like the previous three games, the plot involves Morden doing something evil, but anyone who has played 2 or X knows the aliens are the true villains. Furthermore, 99% of people who play Metal Slug games don't care about the plot and care more about shooting stuff, dying a ridiculous amount of times, and swearing at this game for being really, really, hard.