They may not be tough enough? Then I'm sure Changed: Doomsday will be your choice.

This mod allows you to make your Changed experiences more challenging with new gamerules.

Only gamerules are added. It's fully server-side. Your friends may not need to install this mod.

The mod is still in an experimental phase, but it's stable currently.

Currently provided gamerules are as follows:

1.0 (Current Version)

Doomsday - Default: 0 (Ingame display name: changedDoomsday)

If enabled, latexes will remain hostile to all players, regardless of whether they're transfurred. Set to 1 to enable, and 2 to include organics. (Tamed latexes and latexes of the same faction as you won't attack you.) (You'll be their first target!)

Note: Currently, only 2 latex factions exist in the Changed MC mod: Pure White Latex and Dark Latex. Becoming a Shark Latex doesn't mean other Sharks will stop attacking you.

NowhereToRun - Default: False (Ingame display name: changedNowhereToRun)

If enabled, they (hostile latexes) can see you through the walls and try to raid you. (If you're in their detection range.) (They only see players!)

Contagion - Default: 0 (Ingame display name: changedContagion)

If set to 1, latexes can transfur any transfurable entities by only one hit. (Environmental hazards included. Affects only players if set to 2. Setting it to 3 will not affect players.)

Note: Overwrites 1 attribute changed:transfur_tolerance to 3. Equipping armors with Latex Protection can help you temporarily resist one infectious punch.

Threats From Afar - Default: 100(%) (Ingame display name: changedThreatsFromAfar)

(This function is not completed. They will ONLY target you from afar! Values cannot be lower than 100.) This value will multiply latex NPCs' eyesight. Set to 200 or above to make them see very clearly. (Increasing this value with Nowhere To Run enabled can bring you better experiences.)

Note: Overwrites 1 attribute minecraft:follow_range. Equipping armors with Latex Protection can help you temporarily resist one infectious punch.

It only requires Changed mod to work.

Credits

ltxprogrammer - Provided Changed MC mod

MCreator - Provided assistance

CS630636286 - Made this mod and the picture, The Doomsday

Yea- it's made with MCreator, but I also changed its code a bit, so it'll be more flexible for me to add gamerules.

You may provide your issues or advice by posting a comment. (Although I don't have much spare time on this project, I may take a look at the comments occasionally.)

Some kind of relaxing gamerules are considered, but they will be temporarily delayed, because of my limited technology. (I just started researching MCreator and JavaScripts recently so)

As usual, enjoy the nightmare we keep looking for