How to change a game rule:

/gamerule doInsomnia false

List all game rules:

/gamerule

List of game rules I care about:

# Java edition & Bedrock edition:
/gamerule doInsomnia false
/gamerule doFireTick false

# Bedrock edition:
/gamerule showcoordinates true

Other ones:

# List of Bedrock edition game rules and their defaults:

commandblockoutput = true
dodaylightcycle = true
doentitydrops = true
dofiretick = true
recipesunlock = true
dolimitedcrafting = false
domobloot = true
domobspawning = true
dotiledrops = true
doweathercycle = true
drowningdamage = true
falldamage = true
firedamage = true
keepinventory = false
mobgriefing = true
pvp = true
showcoordinates = false
naturalregeneration = true
tntexplodes = true
sendcommandfeedback = true
maxcommandchainlength = 65535
doinsomnia = true
commandblocksenabled = true
randomtickspeed = 1
doimmediaterespawn = false
showdeathmessages = true
functioncommandlimit = 10000
spawnradius = 10
showtags = true
freezedamage = true
respawnblocksexplode = true
showbordereffect = true
showrecipemessages = true
playerssleepingpercentage = 100
projectilescanbreakblocks = true