Europa Universalis IV

DIPLO ANNEX ONLY (CORES ONLY will be allowed by Austria, NO CLAIMS) (no conquest in the HRE)
Mil Tech and Diplo Ideas are critical to success, traditions make your armies melt enemies. With the right Ideas you can get up to 9 vassals at a time (late game)

I also used a huge galley spam to deal with the Baltic Sea

Get your main trade node to Lubeck. Land node sucks balls. Then build light ships and pirate Novgorod to annoy Russia (they never fought them off)

Kill Poland as soon as possible, do not let commonwealth form.
Ottomans and Russia will take turns ganking Poland so hop in.

Either use Denmark to kill Poland or use Poland to kill Denmark. I had Poland inherit Denmark and then stole Denmark from a weak Poland

Use Austria until the league war then ally one of the GPs (I used Spain)
If you are strong enough and sick of waiting just fight Austria with GP ally and just kill as much as you can without a coalition firing.

Stay calm and don't rush, it will take time and its tempting to risk coalitions but restarting this achievement is horrible