ACE COMBAT 7: SKIES UNKNOWN

For this one you need to buy up every single aircraft, every single special weapon for every aircraft, and every single upgrade part BOTH in campaign and multiplayer.

Notably, this includes the X-02S Strike Wyvern secret aircraft which only becomes available to buy after you clear the campaign for the first time. The plane costs 2 million points.

All in all, this will set you back more than 30 million points.

Clearing the campaign for the first time grants you one-time bonuses for mission completion, so make sure you get those.

When the bonuses run out, Mission 11 is a good way to farm points in single player, but, provided you are not half-bad, multiplayer is the fastest way to rack up points (you can average around 100k per one 5-minute game). I recommend investing in a plane with either QAAMs, SASMs, or, if you are confident of your skills with it, the PLSL. If you use missiles prioritize missile homing and missile speed upgrade parts.

For anyone wondering, the exact MRP you need to unlock both Campaign and Multiplayer parts is 31,549,000.

More of a tip than a guide, as Bermuda Polygon's solution is well stated, but I did find that when I got down to the last few upgrades, I had trouble locating ones that I might have missed, as I was more strategic than methodical in my selections as I progressed through the game. For me, the missing item was a special weapon buried in the aircraft tree.

This tip really only works for aircraft special weapons rather than aircraft themselves or other upgrades, but if you find yourself in a similar situation of going cross-eyed looking for that last one or two special weapons, I found that by entering my hangar (either in single or multiplayer) and scrolling through the list of aircraft avaiable to me, I was able to find missing special weapons purchases far more easily than trying to find them in the aircraft tree. When looking at your aircraft using this method, it is very easy to confirm on the loadout page in the lower right corner that you have 3 special weapons available for selection....if you don't, you immediately know what special weapons you are missing in the aircraft tree.

I hope this helps someone clean up this achievement that, like me, didn't plan very well going into this.