Nucleus is a tiny 10kb drag-and-drop hardcore survival plugin with 3 lives. There are no configuration options, and Nucleus will automatically set the game mode, server icon, spawn radius, gamerules, etc. I do not recommend using it with other plugins or on an existing world.
Player's lives are visible in chat messages, on the actionbar and in the player list.
When a player dies, they lose a life and their death will be broadcasted:
When a player loses all their lives, they are permanently put into spectator mode: