As for my actual opinion on the game; it's neat! Has some scoring issues that made me nearly tear my hair out but it works well enough as a free one-man project blending 2hu and HLM together.
Though the upgrades and certain weapons are...horribly unbalanced; a common tactic I used to get more money quicker was just to nuke the highest-paying boss stages with the RPG repeatedly, helped by the ammunition upgrades and the ghost attack-twinning.
Turns out when you have iframes, suicide-carpetbombing the enemy is a perfectly legitimate strategy.