Yes, but it is not very readable, as it looks to be generated from Java input, probably through GWT.
Levels are stored as JSON - here is a level 2 file:
{ "camera": [ { "bottom": -51.69, "id": "Slingshot", "left": -28.397, "right": 47.013, "top": -51.69, "x": 28.621, "y": -13.985 }, { "bottom": -49.048, "id": "Castle", "left": 12.344, "right": 82.582, "top": -49.048, "x": 66.776, "y": -13.929 } ], "counts": { "birds": 5, "blocks": 27 }, "id": "pack1/Level57.lua", "scoreEagle": 29000, "scoreGold": 60000, "scoreSilver": 47000, "theme": "BACKGROUND_BLUE_GRASS", "world": { "bird_1": { "angle": 0, "id": "BIRD_RED", "x": 9.93, "y": -4.328 }, "bird_2": { "angle": 0, "id": "BIRD_RED", "x": 7.489, "y": -4.339 }, "bird_3": { "angle": 0, "id": "BIRD_RED", "x": 5.417, "y": -4.249 }, "bird_4": { "angle": 0, "id": "BIRD_RED", "x": 3.42, "y": -4.339 }, "bird_5": { "angle": 0, "id": "BIRD_RED", "x": 0, "y": -1.035 }, "block_1": { "angle": 90.027, "id": "STONE_BLOCK_4X1", "x": 61.498, "y": -7.314 }, "block_10": { "angle": 180, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 74.143, "y": -0.157 }, "block_11": { "angle": 180, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 83.499, "y": -0.107 }, "block_12": { "angle": 180, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 92.925, "y": -0.058 }, "block_13": { "angle": 0, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 7.156, "y": 1.484 }, "block_14": { "angle": 135, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 111.252, "y": -18.195 }, "block_15": { "angle": 24.537, "id": "TERRAIN_TEXTURED_HILLS_5X5", "x": 3.616, "y": -0.22 }, "block_16": { "angle": 45, "id": "TERRAIN_TEXTURED_HILLS_5X5", "x": 11.912, "y": -0.041 }, "block_17": { "angle": 45, "id": "TERRAIN_TEXTURED_HILLS_5X5", "x": 103.199, "y": -0.037 }, "block_18": { "angle": 45, "id": "TERRAIN_TEXTURED_HILLS_5X5", "x": 106.374, "y": -3.514 }, "block_19": { "angle": 45, "id": "TERRAIN_TEXTURED_HILLS_5X5", "x": 109.7, "y": -0.188 }, "block_2": { "angle": 89.999, "id": "STONE_BLOCK_4X1", "x": 68.165, "y": -7.317 }, "block_20": { "angle": 359.713, "id": "PIG_BASIC_SMALL", "x": 85.85, "y": -15.34 }, "block_21": { "angle": 2.262, "id": "PIG_BASIC_SMALL", "x": 75.084, "y": -11.419 }, "block_22": { "angle": 7.16, "id": "PIG_BASIC_SMALL", "x": 68.143, "y": -11.427 }, "block_23": { "angle": 0.153, "id": "PIG_BASIC_SMALL", "x": 61.475, "y": -11.411 }, "block_24": { "angle": 179.984, "id": "WOOD_BLOCK_4X1", "x": 85.911, "y": -13.755 }, "block_25": { "angle": 180.065, "id": "WOOD_BLOCK_4X1", "x": 75.051, "y": -9.834 }, "block_26": { "angle": 180.172, "id": "WOOD_BLOCK_4X1", "x": 68.284, "y": -9.842 }, "block_27": { "angle": 0.112, "id": "WOOD_BLOCK_4X1", "x": 61.463, "y": -9.83 }, "block_3": { "angle": 90.017, "id": "STONE_BLOCK_4X1", "x": 74.983, "y": -7.316 }, "block_4": { "angle": 270, "id": "STONE_BLOCK_8X1", "x": 85.892, "y": -9.272 }, "block_5": { "angle": 359.999, "id": "TERRAIN_TEXTURED_HILLS_32X2", "x": 75.877, "y": -4.433 }, "block_6": { "angle": 225.001, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 98.165, "y": -5.15 }, "block_7": { "angle": 225.001, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 104.615, "y": -11.599 }, "block_8": { "angle": 90, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 64.836, "y": -0.135 }, "block_9": { "angle": 135, "id": "TERRAIN_TEXTURED_HILLS_10X10", "x": 60.034, "y": 1.675 } } }
This means that you could add your own levels by intercepting requests.