I love the concept! Very cool idea - you really have to plan out your strategy and figure out a good balance between offense and defense. It's nerve-wrecking and exciting to move your units to see what they might bump into! You really have to think before you use that last of your 5 attacks - for if you wind up next to someone, you are going to lose it since you can't attack one more time that turn.
You can have a "stalemate" situation where you capture a unit 5 spaces away from the middle, the other player can spawn and capture your unit, and again and again.
Fun board! Many different strategy types, for sure. Good balance between setting up a good offensive push, without making yourself too vulnerable to attack.
Also suggest making a "capture the flag" variation, but the flag carrier would have to be limited to only moving X number of squares per turn.
You can have a "stalemate" situation where you capture a unit 5 spaces away from the middle, the other player can spawn and capture your unit, and again and again.