Their singularities are constructed with dust and strategic resources. Despite Riftborn population being pretty good, they need to waste time constructing them as well as their singularities. I'd say their main weakness is that they also often need to manually construct their manpower for wars since they do not automatically get manpower from food (because, yuck, organics).

That ^ with a little plus of very specialised shiphulls. Their attackers have many weapons, but are very squishy. That may be a weakness esp in early game, too.

If you wonder what the weaknesses of a faction are, it often helps to play them once or twice, you get a better feeling for areas that may be slower. (You can ofc always ask here, too.)

Riftborn are quite weak in early to midgame in my experience and excell in lategame.

Their need to build population and manpower manually means that riftborn live or die by their number of systems.  Ideally they'll have one system dedicated to just constantly producing manpower, one for shipping out new population and another churning out new ships.  Find those systems by any means necessary and find a way to shut them down.  Get sleepers on their systems to identify where their main breadbaskets are and interfere with them however you can.  If you have the chance to hack their home system, force them to change government types to ecologists; the food laws are all but useless for riftborn compared to the orange.  Even if they embrace the green, they'll just be growing their substandard minor pops faster instead of their superior major pops, which is a win for you.

Knocking out one or two of riftborn systems can put a serious dent in their production schedule; whether by hacking or invasion you have to be aggressive against them to keep them from going too wide.  Once they get 5+ systems running they build tremendous momentum and can put out swarms of ships in a hurry.  If you ever, and I mean EVER, spot one of their colonization ships, KNOCK IT OUT.

Consider using things like boarding pods and/or weapons that cause extra crew damage in battle to turn their industry against them; if you can drain away their excess manpower or take it for yourself you can trip up riftborn quite handily.  If you can go for the ion wave behemoth tech you can wipe out entire fleets at a time no matter how much they produce.  There are counters; you just have to deviate from your own plans a bit to exploit them.

Thank you Generals! here is the thing: I'm allied with the Riftborns but I'm studying the possibility to go for a supremacy victory in the future.Currently, they are the strongest empire followed by me since we are in the middle reaching the end game. Like I said, they already have insane ways to produce FIDSI and a battle against them in the end game, well, probably is going to be crazy. But I'm really happy with this - it will be quite a challenge if I decide to battle them. Can it happen they betray me kicking me out from the alliance to declare war against my empire ? What can happen if I kick out another ally from our alliance and declare war against him? Will the Riftborn become pissed off and declare war against me ?

Mourioche wrote:

...build colons as early as possible ...

ha. it seriously took me a second. I was .... I was like wha?

EDI wrote:

Can I assume the empires' powers are unbalanced that is, there are very strong empires while there are others not that powerful even if they have unique mechanics?

Not intentionally by design, I imagine. But sure. but those kinds of things only really crop up on competitive multiplayer. Single player can be done on Endless Difficulty equally with any faction.