Try the Xtreme Wars one, it has no producing capability , but close what you expect...

Actually it had tremendous firepower and range for its cost. It outranges the megalith even. So you can kill them if you have the room to kite them. When I played UEF I would easily have 3 FB focus down a megalith. If they had 3 Megas I would have about 9 of those. Also use them to make those nice tanky high damage splash T3 units so nothing can rush up on your FB.

for me the fact that you can create those experimental units super fast as uef makes them realy realy good

for me its the best unit , i just dont push it into base rather slow pushing to control map and building army and def near enemy , if you control map you control battlefield and you will win

although it has the longest range in game hahahaha

All about how you use it

UEF Are best as a turtle faction for sure

Jill is right,
honestly a great strat is to build a fatboy and deploy it in a area where it can rapidly build units.
many times i built like 4 fat boys to build a little defensive position on 2 parts of the map, rapidly building mobile shield generators, artillery units, anti-air units and mobile missile launchers

"think more of it as a support unit than a tank" like all of the experimentals they are support units and force multipliers rather than being amazing by themselves.

Until it somehow gets stuck on terrain, then it's a "immobile base"