Great game. My only comment would be to put in a death counter and maybe shorten it up a little bit. I kind of had a "are we there yet?" three quarters of the way through. 4/5
The best bonus upgrade is the Antimatter Shield, you can literally win levels by just stalling until time runs out. LEVEL 1: after you beat it, buy the first level of E-I. Save up you money until the third level and buy another E-I. By level ten you should have three levels of E-I, one level of S-B (shield bounce), and the Sticky Shield. What not many people know is that you get EXTRA BONUS UPGRADE POINTS for defeating the boss tank! If you defeated the boss tank you should have five bonus upgrade points saved up. Spend them on the Antimatter Shield, and wait five more levels to get Heatseekers. ALWAYS KEEP LOTS OF MONEY IN RESERVE, you will need the interest gained from stockpiling it. The further you go, the more E-I you should buy. The other cash upgrades aren't very important.
Give this a plus up if you get a hard badge from following this guide!
Spider Tanks are extremely effective for mission nine! They make it too easy. Another great game in the series, I'm gonna finish the next one right after I finish the last mission.
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