BEATING LOKI: Use the Odin ship with the Excalibur weapon and dodge/shoot until "device overdrive" special is charged. Then abuse Odin's invulnerability to get to 200k chain so you score 50%+ bonus to special when invul wears off. Survive until you can fire special a second time. That last special should get you past him. To unlock Odin, beat lv20. To unlock excalibur, beat lv19 with only the first weapon (not as hard as it sounds with upgrades - if you need easy gold, play lv16 over and over). IF THIS HELPED COPY-PASTE AND KEEP IT ALIVE.
To beat bonus map, defend the land part (you'll need a tank and AA, maybe 2), the turrets should make this easy. Focus on building a navy (hunter support, corvette and sub) and a fighter. Use infantry to capture the island bases. Mass air units to destroy enemy turrets.
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