Here's some more mods that are compatible with TFG but aren't included by default. Feel free to add them to your own instance of the modpack!

Visual

• TFC Caelum (CF, MR) - a realistic sky mod that shows planets, accurate constellations, moon phases, and so on. Also adds rainbows! Not included by default because it crashes MacOS clients.
• Xaero Zoomout (CF, MR) - Lets you zoom out further on the map.
• Distant Horizons (CF, MR) - TFG comes with configurations to get it working with TFC's world generation.
• BlueMap - TFG comes with a resource pack for it to work with some of TFC's blocks.

Third Person

• Shoulder Surfing Reloaded (CF, MR) - Improved third person camera mod. Client-side, so you can install it even if you're playing on someone else's server.
  • Third Person Shooting: Zero (CF, MR) - Adds compatibility between Shoulder Surfing Reloaded and TACZ (the gun mod)

Content

Addons

• Epic Knights of TerraFirmaGreg (CF) - Adds additional weapons and armor to the TFC era of the modpack. Not included by default because of a lot of extra equipment bloat.

With Custom Recipes

• Create: Sound of Steam (CF, MR) - expands on create's Steam Whistle and adds a ton more options to let you play music. Not included by default because of how niche it is. We include our own recipes for it though.
• Chimes (CF) - adds some wind chimes. Not included by default to avoid modpack bloat, but we do have our own recipes for it.
• Create: Extra Gauges (CF, MR) - expands on create's factory gauges. If you add it to your modpack, you'll get TFG recipe changes.
• Immersive vehicles: (CF) and its official addons with TFG recipe support by @ilikecupcakes
  • MTS Official Content Pack (CF) Adds dozens of cars, planes, helicopters and tanks. As well as road signs/lights. Requires the base mod and the official automobile pack for recipe support.
  • MTS Official Automobile Pack (CF) Adds several new cars. Requires the base mod and the official content pack for recipe support.