The Splash Mine is actually the first weapon you start with in the game. It is also the cheapest (Normal Arm doesn’t count), with a rather wimpy upgrade cost of 5,400z, which certainly shouldn’t be a problem. Heck, you should have this thing fully upgraded right after the fight with the Bonnes, if not beforehand.
When used, Megaman places a small mine on the ground. Anything that runs over the mine causes it to explode, and the enemy takes a decent amount of damage. The mines will also detonate after a certain amount of time has passes. You are allowed to have 4 mines on the ground at one time, and with the energy maxed out, you have a total of 48 mines from the get-go. This is also the only weapon in the series capable of hurting the user. If you walk over one of them, you will take a negligible amount of damage. If your armor is upgraded to at least the Flak Jacket, the damage is nonexistent, but you’ll still reel backwards.
The mines don’t do a large amount of damage on their own, but they can be used strategically against enemies. Placing 4 of them on the ground when a Sharukurusu is charging you is a smart move, as it will take a rather large chunk of damage, and fall in the process. A lot of the more mobile enemies are more vulnerable to this weapon as well. This is also the best weapon for taking out the treads of the Marlwolf, and it does a good job taking out the bot itself when mines are placed in the hatch.
This weapon does have its fair share of shortcomings, however. While this weapon may be used nicely on mobile opponents, certain stationary enemies may pose a threat. Firushudot will most likely knock you out if you try to use this weapon on it from close range. Some stationary opponents like the Bonne’s Leopordo or Orudakoitan may be easy to take out with it, but others aren’t so generous. Also, Karumuna Bash is pretty fierce, and may give you problems when trying to use this. This weapon is also rather useless in a fair amount of situations, like the Barcon or Gesellschaft/Fokkerwolf battles.
The Splash Mine is a pretty unique weapon, allowing you to set up on more mobile opponents. However, it does have the setbacks of being useless in certain places, as well as being hard to use on certain opponents. I give the Splash Mine a 7/10. Fun to use, but useless at some points.