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KSP2 is still in active development and there are several engines and fuel types yet to be added to the game. However, the methalox department seems to be pretty complete and appears to be largely the same as it was in KSP1. I’ve been comparing the engine specifications for KSP 2 and sadly found that they are just as imbalanced as before, if not worse. I think there are a couple of possible fixes, which I would like to discuss in this topic. In Developer Insights #17, Nertea wrote a neat article about engine design, in which the new approach to engine archetypes was explained: Deep Space for optimal fuel efficiency, when thrust is not that important; Orbital when you need sufficient thrust for some maneuvering. Sustainer for optimal atmospheric performance with good thrust. Launcher when you need maximum thrust. I think this is a great setup, which already provides a much better guideline for choosing the right engine. The same article also stated 3 design principles: Don't deviate from KSP1 for the sake of it. A methalox rocket in KSP2 should perform similarly to a similar looking Liquid Fuel/Oxidizer rocket from KSP1. Engines of an archetype have similar characteristics. Engines within a fuel type exist in a similar band of power, so newer or larger engines should not make older engines obsolete. Because these principles are not always compatible with each other, some choices have to be made. For example, the Rhino had way too much thrust for an orbital engine and it looks more like a sustainer anyway, so its Isp stats were changed to fit the sustainer role. For the orbital role, the Labradoodle was introduced. This makes for better gameplay and therefore the deviation is justified. In most other cases though, engines have been kept pretty much the same as in KSP1, even where change is definitely in order. In my opinion, the methalox category should just consist of a simple, balanced set of 12 basic engines. One per archetype of each size and nothing more . This is already true for the LG and MD sizes, but not so much for the SM and XS sizes: First of all: the Reliant is terrible. While the Mammoth II and the Mainsail put out about 2.5x the thrust of their sustainer counterparts, the Reliant only provides 20% more thrust than the Swivel. It also still lacks any thrust vectoring, which already was enough reason to never use it in KSP1. However, like with all launchers, its sea level Isp has now also been nerfed to below that of the Swivel, making it utterly useless. The second design principle states that the Reliant should be proportional to other launchers, which means that it needs thrust vectoring and its maximum thrust should be increased dramatically to about 550 kN. While the TWRs of orbital engines are consistent across all size categories, the Swivel and Reliant TWRs are a bit low compared to their larger cousins. Their masses should be adjusted to about 1100 kg for the Swivel and 2100 kg for the 550 kN Reliant. It’s unclear to me what the roles of the Thud, Twitch and Spider are. Being radial engines, it’s easy to attach a lot of them to a rocket , providing plenty of thrust. However, their TWRs are too low and their sea-level Isps too high to be considered proper launchers., while their vacuum Isps are too low to be considered good sustainers. I think instead of having dedicated radial engines, radial engine plates would provide a lot more versatility. In the XS size there are no launcher or orbital engines. One option would be to refit the radial engines: the Twitch could easily be repurposed as a launcher by nerfing its sea-level Isp to 255 and increasing its TWR to around 25. With 3- or 4-symmetry it already provides sufficient thrust, so its mass would be lowered to about 65 kg. Changing the Spider into an orbital engine requires a bigger overhaul: Isp needs to be 330/165 and TWR about 12. Assuming 8-symmetry (because Spider), its thrust should be cut down to 0.75 kN and its mass to 6.5 kg. As a deep space engine, the Ant's Isp should be adjusted to 365/55 and its TWR lowered to under 8. To keep engine ratios similar to larger sizes, its thrust should be doubled to 4 kN and its mass increased to 55 kg. Last but not least: the Vector is spectacularly overpowered. It outperforms the Swivel, the Reliant and even the larger Skipper in both thrust and atmospheric efficiency, effectively making all of them obsolete. Even though it’s unlocked somewhat later in the tech tree, it brutally violates the third design principle and therefore has no business in the methalox category. Advanced and specialized engines such as the Vector and the Dart need a different fuel and since hydrogen is already an existing fuel type, a hydrolox category would be an excellent solution. This would also be realistic considering the real-world analogs of the Vector and the Dart.