Not sure if a bug (?) but it's possible to purchase the Ankh more than once, even thought the description says usable only once per game. Doing so does not grant you an extra resurrection, and upon returning to the upgrades menu the skill level is back to 1.
Adding to the physics lab comment: do NOT spam them in defence missions. You can easily hit the ship cap and prevent further waves from spawning, effectively leaving you in limbo and unable to complete the mission.
Something needs to be done about physics lab stacking. The easiest way to win is to plop down a few fighter miners and interceptors/gunships + a few physics labs, build an annihilator starport, then spam physics labs. An unending stream of fighters and titan cannons wrecks absolutely everything, including your FPS. A cap on the speed bonus would be a great idea.
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