JED 1.6.0+ - Creative test world

{
    "dimensions": [
        {
            "dim": 8,
            "dimensiontype": {
                "id": 8,
                "name": "Custom Superflat",
                "suffix": "_dim8",
                "keeploaded": false,
                "worldprovider": "WorldProviderSurfaceJED"
            },
            "disable_teleporting_from": true,
            "jed": {
                "ForceGameMode": true
            },
            "worldinfo_onetime": {
                "generatorName": "flat",
                "generatorOptions": "3;minecraft:bedrock,62*minecraft:dirt,minecraft:grass;1;",
                "GameType": 1,
                "DayTime": 6000,
                "GameRules": {
                    "doDaylightCycle": "false",
                    "doWeatherCycle": "false"
                }
            }
        }
    ]
}