Omgen

Omgen is a mod, that uses JSON to create "Generation entries". Those entries consist of a condition (for example, what fluids must interact, where should they be in relation to each other etc.), and the generation itself - all the possible blocks/block tags that could generate with a certain weight.
This mod is intended for use of Forge modpackers. It's not perfectly tested yet - but that will be done in the future.
It supports JEI too - every single generation entry you create will be displayed in JEI:

(Image will be added soon)

I'm a modpacker. How do I add a generation entry?

Just like you would do in a datapack with data/minecraft/recipes/myrecipe.json, put your json file into this directory: data/omgen/gens/myentry.json
Your JSON file should follow this format:

Available keywords are (< > is must, [ ] is may):
<primary> : Fluid ID or Tag that represents the main fluid .
[secondary]: The second fluid ID or Tag, that represents the other fluid (may not use, which means no second fluid needed for interaction).
[secondary_pos]: Represents the way liquids must interact in order for conversion to happen:
- "Neighbour", "N", "n" or 1: Newly placed liquid block must be neighbouring with the secondary fluid.
- "Replace", "R", "r" or 2: Newly placed liquid block must attempt to override the secondary fluid block (for example, drop onto it from above).
- "Doesntmatter", "D", "d" or 3: Both variants listed above work.
Defaults to "Doesntmatter".
[above]: Block ID or Tag that represents block ABOVE the interaction point.
[below]: Block ID or Tag that represents block BELOW the interaction point.
[around]: List of block IDs or Tags that represent blocks that may be AROUND the interaction point. Order doesn't matter. Count here must not be bigger than 4. Repetitions are allowed if you want multiple blocks of same kind.
[priority]: Positive integer that represents priority of targeted gen over others in case of conflict. Larger number represents larger priority. Defaults to 100.
[min_height]: Sets the minimal height at which interaction must happen for the generation to occur. Defaults to current world's minimal build height limit if not specified.
[max_height]: Sets the maximal height at which interaction must happen for the generation to occur. Defaults to current world's maximal build height limit if not specified.
<gens>: List of lists, where first element is a weight (how often this block/block tag should appear in relation to others), and second element is Block ID or Tag itself.

If you want to use Tag anywhere, you MUST put # in beginning: "minecraft:oak_log" is a block, "#minecraft:logs_that_burn" is a tag.

If priorities of two or more conflicting gens are equal, only one of these gens occur randomly with equal chances.

A short showcase video that shows how some possible entries work: https://youtu.be/vV8fa0XR4Wc