Idea: everytime a frame passes, theres a one in a hundred thousand chance to close/crash the game. (you can also make it just leave the current world your playing on.)

Idea: every few minutes, offset the cursor by one pixel.

a few ideas: remove all character creation options but mediumcore, make so the player can't breathe in space, moves slower in the underworld and can't regenerate life while down there, make so that falling stars also damage the player, make so that every time the player dies they respawn at a random point on the map (including lava), make so that running at a high speed and colliding with solid blocks or enemies deals more damage (to the player) depending on how fast they move, make so that at a random time the player gets inflicted with a random debuff for random time and a 1/1,000,000 chance per frame that they get a random permanent debuff (that can't be removed by any means, including accessories), make so that any item can burn in lava regardless of its rarity, make so that if you are holding an item of a certain damage class (for example, melee) and while you are holding it the drop rates of all weapons of this class have their drop rates reduced by 99% (including boss/treasure bag loot)... i have a lot more ideas, want me to continue?

every ore costs double to make their armor and tools.

Every gold chest is a dead man's chest,
Every spawn of a demon eye or blue slime can become the eye of cthulhu or king slime respectively
Nerf the wand of sparking
add bees to the forest

make the cursor invisible

make the prices alot higher and npcs can harm the player

town npcs can actually hit you if they throw a projectile

can you make every boss 30% bigger

and make gills potions make you have to breathe water instead of air forcing you to be underwater until the potion ends

and make moonlord have a chance to do an extra like blink whatever its called when hes about to spawn

everytime moonlord shoots the deathray make the screen blink like the last person said

-Life crystals have a 50% chance to be life crystal boulders
-All dart traps are venom traps
-You drown twice as fast and water inflicts slow and obstructed on you
-Every form of damage inflicts bleeding
-Landmines generate everywhere
-Every boss is twice as fast and starts their second phase or max attack speed 25% hp earlier
-Night time passively gives you the blackout debuff
-Towns don't decrease enemy spawn rates anymore
-Touching torches, campfires or basically any light source that uses fire sets you on fire

1/20 chance to watch a 15 second unskippable ad, enemies can still hit you

can you add tripping like that one super smash bros game