Survival O' the Fittest

This literally stops you from punching trees. It does so very unoriginally, allowing you to make a flint hatchet like so: 

and making string with plant fiber, gotten when breaking like any plant you can think of (except flowers), like so:

Where things get interesting is when you try to mine stone like usual and it doesnt drop you anything, where you have to resort to breaking down Light Stone to get Loose Stones. 

Light Stone can be found in tall boulders in flat biomes, or in blobs under the world, the lowest at y56. Using the Loose Stones, you can make cobblestone like so:

This mod was made originally for a modpack i was working on for a youtube video, but that project has been abandoned. 

If you want to add compatibility, with tags, here are my custom ones:

survival_of_the_fittest:fiber_harvestable - Blocks that can produce Plant Fiber upon breaking.

c:flatland - Biomes the light stone boulder spawn in, by design flat biomes only.