In HOI3 the SU was always my favorite country, but I found it too easy because it always just resulted in Germany running out of manpower and then me pushing them to Berlin with ease. So I added something alone the lines of anyone in the axis faction gets +200% manpower, +50% IC +100% resources. I don't remember what the exact values I used, but it ended up with Germany being capped in all resources, having a ton more IC then normal, having a bigger than usual army and having essentially unlimited manpower.
They Germans walked straight to Moscow like it was nothing. I made them an unstoppable juggernaut and overestimated my abilities.
. So many great memories from HoI3. My favourite moments were when I was first learning the game, managing to stop the Germans in Belgium playing as the Brits (I can pull it off more often now - although not always - but back then I was quite happy with how I'd done), and playing as Australia and leading the invasion of both Japan and Europe (helped by a fair dollop of expeditionary forces - most of the US and UK's armoured divisions were under Australian command, lol) - this was because the AI couldn't cope with naval invasions, so kinda had to do it m'self, but it was kind of cool liberating Europe (after the USSR had fallen) as the Aussies - Aussie Aussie Aussie! Enjoyed playing as everyone else as well though - can't wait to tear into HoI4 
