The guys over at AccidentalGames have come up with a pretty clever system! Have you ever wanted to have some clever mods in your game, but couldn't figure out how to work them? Maybe you want to keep Minecraft "vanilla", but still want to try out some neat new things? Gamemode 4 might be exactly what you're looking for!
Gamemode 4 is a collection of carefully constructed redstone modules, they can be easily added to your Minecraft world to add to your game-play experience without the need for mods! While they aren't technically capable of the same level of sheer game-editing audacity as some mods do, Gamemode 4 is still a pretty impressive setup: Bat grenades, potion swords, social creepers, deepening snow, Ender shields, dragon hatchlings, buried treasure, and a whole mess of others are all possible, using only redstone and command blocks!
Aside from downloading a world or schematic, it's also possible to integrate any of these into existing games with a command block: each module on the Gamemode 4 site has a 1-click option, that will give you a line of text to copy-paste into a command block. Just paste it into a command block in your world, give it redstone power, and off you go! Amazingly simple to use for such a diverse set of neat modules.
Ready to check it out for yourself? Hit up the Gamemode 4 site!
Want to see some of these modules in action before trying them out? Each one of them has a video showcasing what they can do!