Version Roadmap

Version roadmap

Which legacy Minecraft versions the layer supports or will support, in order, and why. Written 2026-11-06. Back to Home.

#	Version	State	Why here	Approach
1	1.7.10	Beta	Huge pool of mods with no modern port (Thaumcraft 4, Witchery, GTNH, the Reika mods...)	Hand-written shim over 1.21.1
2	1.12.2	Alpha, beta when its top libraries and content mods are playable	The largest old pool of mods with no modern port	Hand-written shim (169k lines)
3	1.6.4	Started	Closest old version to 1.7.10 (same cpw.mods.fml packages); cheap	Thin forward layer over the 1.7.10 shim: numeric ids, Icon, old packets (estimate, corpus)
4	1.5.2	Planned	Same numeric-id and old packet model as 1.6.4, so a small delta while that work is fresh; the FTB Ultimate/Unleashed era with mods that exist only there (Thaumcraft 3, early Railcraft/Forestry/BuildCraft, Equivalent Exchange 2)	Delta over the 1.6.4 layer
5	1.4.7	Started (groundwork)	Same model; the Hexxit era	Delta over 1.5.2 plus obfuscated/flat class names, ModLoader BaseMod mods and sprite-sheet textures (estimate, corpus)
6	1.20.1	Started (experimental)	Largest Forge ecosystem; most popular mods have 1.21.1 ports, so the value is the abandoned set; its pipeline is the base of the next three	In-place bytecode migration onto NeoForge 1.21.1 (estimate)
7	1.19.2	Planned	Big modpack base, many mods stopped here	1.19.2 to 1.20.1 renames and diffs on top of the 1.20.1 pipeline
8	1.18.2	Planned	Same	Same, one step further back
9	1.16.5	Planned	Many abandoned mods and packs; Forge 36 still used MCP names	Same pipeline plus the MCP to Mojang names step
10	1.2.5	Planned	Tekkit Classic / RedPower 2 era: mods that exist nowhere else	Different layer: ModLoader/BaseMod emulation and flat names, no FML
11	1.3.2	On demand	Few mods	Only if a specific mod needs it

Estimates (wall-clock, 2026-11-06 evening; plus or minus 50%)

Item	Estimate
1.6.4 server side	2 to 4 hours
1.6.4 supported (a handful of content mods playable)	1 to 1.5 days
1.5.2	about 1 day after 1.6.4 loads, overlapping
1.4.7	1.5 to 2.5 days after 1.5.2 (revised 2026-11-06 after the corpus: sprite sheets, ModLoader)
0.4.0 (1.6.4 + 1.5.2 + 1.4.7)	about 4 to 5 days (range 3 to 6)
1.12.2 beta	about half a day (rendering issues #169 to #172, then a re-sweep)
1.20.1	corpus 1 day; first mod 1 to 2 days; broad coverage 1 to 2 weeks
1.19.2, 1.18.2, 1.16.5	1 to 2 days each after the 1.20.1 pipeline
1.2.5	2 to 3 days (a different layer)
Fabric 1.20.1 via Sinytra Connector	3 to 5 days after Forge 1.20.1 works, if the corpus justifies it

Always in parallel: keep the layer able to follow newer NeoForge/Minecraft host versions (1.21.4 and later). That is not a legacy version but it decides whether any of the above keeps working.

Not planned

• 1.8 to 1.11.2: nothing useful lives only there (decision of 2026-10-25).
• Beta, Alpha, 1.0 to 1.1 (ModLoader/jar-mod era): most mods patch minecraft.jar itself (replaced vanilla classes), which cannot be translated as a standalone jar.

Evidence

Mod counts per Minecraft version from several sources (all fetched 2026-11-06 unless noted). Modrinth is biased toward new versions: it is a newer platform, so most old mods were never uploaded there. Use the CurseForge columns for old versions; Modrinth is shown to make the bias visible.

Version	CurseForge (site search, version= filter, all loaders)	CFLookup, Forge only, whole 1.x family	CurseForge via a forum census, April 2023	Modrinth (Forge category)
1.2.5	108	220 (1.2)		71
1.3.2	91	123 (1.3)
1.4.7	175	409 (1.4)		77
1.5.2	404	605 (1.5)		74
1.6.4	851	1,339 (1.6)		131
1.7.10	5,229	6,893 (1.7)	about 4,300	897
1.12.2	10,000+ (the site caps the count)	15,199 (1.12)	about 10,620	2,748
1.16.5		25,806 (1.16)	about 14,440	4,295
1.18.2		17,585 (1.18)	about 11,380	6,072
1.19.2		30,475 (1.19)	about 9,280	8,197
1.20.1		31,887 (1.20)		25,526

The bias in numbers: Modrinth lists about 6 times fewer mods than CurseForge for 1.5.2, 1.6.4 and 1.7.10 (74 vs 404, 131 vs 851, 897 vs 5,229) and about 4 times fewer for 1.12.2 (2,748 vs 10,000+); the gap closes only at 1.20.1 and later.

Modpacks (CurseForge, April 2023 census): 1.12.2 about 20,920, 1.16.5 about 12,180, 1.18.2 about 5,660, 1.7.10 about 4,700, 1.19.2 about 4,160. So 1.12.2 is by far the most played modded version, with 1.16.5 second.

What this changes in the order above: nothing yet, but it sharpens three points. (1) 1.16.5 is the second largest old pool (about 14,000 to 26,000 mods, depending on the source), larger than 1.12.2 in mod count, so its slot after the 1.20.1 pipeline is about the pipeline, not the size. (2) 1.6.4 (about 850 to 1,300 mods) is about twice 1.5.2 (about 400 to 600), which is about twice 1.4.7 (about 175 to 410), so each step down the old versions is worth about half the previous one while costing much less; that supports doing them as cheap deltas right after 1.6.4. (3) The 1.2.5 pool (108 to 220) is the smallest of all, which fits it being last among the planned versions even though some of its mods exist nowhere else.

Caveats: CurseForge's search count includes every loader and any project that lists the version, and caps at 10,000. CFLookup counts Forge projects for a whole 1.x family (1.7 includes 1.7.2 to 1.7.10) and several versions overlap between mods. The forum census is a person's count from 2023. None of these is the number of abandoned mods (the ones that matter here), which needs a per-mod check against NeoForge 1.21.1. Compatibility data in docs/data/mods.json currently rates 86 1.12.2 mods "works" or better and 202 1.7.10 mods. Effort figures use the project's measured pace (about four weeks from the first commit to two shims and the 1.20.1 groundwork).

Sources: CurseForge search with the version filter, CFLookup Minecraft mod stats, Minecraft Forum: What version have the most mods?, Modrinth search API.