They cant be fixed imo. (How do you Fix a Paragon without making T3 Eco useless, how do you Fix T4 Arty without making it imba or T3 arty more useless, how do you fix a T4 Nuke without making a T3 Nuke useless?)
They can most certainly be fixed. Contrary to what a person looking at the games played might think, there are maps in this game FAR bigger than those usually used. The 81K maps are absolutely flipping humongous. You compare them to T3? Well, the fact is that T3 is ALREADY useless on these maps, as it can't reach the enemy, and by the time it does that enemy is capable of having built a base which is impregnable to ANY T3 force. Even base-breakers like the GC and Spiderbot cannot do anything at this stage; they take too long to get there, and are not strong enough for when they do. This is where the higher end weapons like T3 Artillery come in. Useless in a usual game, yes, but building 2 dozen of them in stealthed locations in range of the enemy CAN and DOES break the base, unless the enemy wises up and finds them out. This is where the Game-Ender becomes necessary. It is not a case of buffing T4 makes T3 useless, but a case of T4 gives possibilities for when T3 simply is not viable.
In response to the OP, definitely the Game-Enders should be a Strategic option to be used where all else has failed. They can be stopped by smart play, so they are not Wonder-Like, but they will, in my mod, be INCREDIBLY strong. If you build one, and it is not dealt with, you WILL win the game. I do not intend for them to ever be an efficient, or even viable, option in maps smaller than 40K, except for the very worst of stalemates.
Just to lay it out, my intentions for the modification are:
Salvation - Undecided. See my poll to decide for me
Mavor - The ultimate in Assassination weaponry, and the longest range, most strategic weapon in the game. Build this, and if you can keep your target visible, that target WILL die. NO amount of dodging or protection can hold off Mavor forever.
Scathis - The ultimate in Base-Breaking weaponry. A mobile artillery platform with significant defences of its own, once a Scathis is in range of your base, that base WILL be wiped off the map. NO amount of shielding can defend against this threat for any significant amount of time.
Paragon - Not a weapon on its own, as such, Aeon engineers decided that the current weaponry available was enough if only you hit the enemy with MORE of it. The Paragon generates infinite resources for as long as you have the build power to use them. A Paragon will ensure that you can hit the enemy with so much fire-power NO defences can hold before you, and NO assault can overwhelm you.
Yolona Oss - The ultimate in wiping out any unprotected target you damn well please. If it does not have SMD cover, it WILL die. To achieve Game-Ender status, Seraphim engineers introduced a way to make it practically impossible to defend a base against a Yolona Oss for a long period of time. Eventually this WILL break through ANY SMD system, and everything below it WILL die.