General progression design

Pre LV

First player need to build Coating shrine. This multiblock open access to some new material, most useful of them for know is lava-coated still that allow player upgrade their boilers.

MV

Mv opens access to aluminum for aluminum bronze and infernal alloy. Also, mv circuits, which combined with infernal alloy required to make Infernal boiler, first steam producing multiblock of GregTech True Age of Steam. Player would also need Cooling box to cool maintenance fluid that is required to get infernal slug and process it into purified infernal dust.

Infernal boiler can and should be upgraded with better coils and better power hatches on the way, as it boost power production greatly.

Infernal alloy also opens tier 2 of single-block steam boilers. At this phase they are probably quite useless, but suppose to have some niche uses.

HV

HV is supposed to be a huge Age. First and most important material is probably a conceptualized steel, that can be used to craft Concept Infusion Matrix. You will also need infernal circuit to craft it.

Concept Infusion Matrix opens access to crafting concept catalysts which allows to craft plethora of different metals.

Industrial gas pressurizer is the next in line. Infused with compression concept, this machine allows you to compress steams into their dense variants. This transaction usually leads to volume loss, but with some compression strings and perfect conditions it can even lead to volume increase.

Spawner extraction machine allows player to harness spawners and build automatic farms from it. This multiblock also provides better infernal slug and blaze source. And also opens second tier of water - Hellish water.

Industrial coating line is direct upgrade from Coating shrine, finally fully automatable coating method.

At this age player also can upgrade Infernal boiler with beating husks so boiler can produce critical steam variants.

Heating cometal also used to create tier 3 of single-block boilers.

EV

Regulated Cryo Chamber is somewhat upgrade from Vacuum Freezer. It provides EU-free parallels and speed boost in continuous crafting.

Cooling tower is direct upgrade from Cooling box, which is just 16 times better in terms of cooling capacity and its aggregation speed. Also, 10 times faster.