Melon Bomber isn’t on Fretta, but it’s still sort of alive.
Alive in the sense that the base itself is fixed up for gmod13, but also dead in that none of the gamemodes made for it work right off the bat, which since you’re not looking for that, you’ll be fine. There’s a copy of Fretta that comes with Prop Hunt but that’s poopy, so use NoxiousNet’s version instead:
To set things up for Fretta, you’d want to modify this template inside the gamemodename.txt file:
"svr" -- gamemode folder name
"base" "fretta13" -- the base you're deriving
"title" "Duck Hunt" -- Gamemode name
"menusystem" "1" -- If you want it to show on the gmod gamemode button
"maps" "dh_" -- Map prefix associated on the singleplayer menu
"selectable" "1" -- Whether it should be selectable on the fretta vote
"1" "dh_" -- Map prefixes you want to show up on Fretta.
Then inside shared.lua, you’d have
And that’s literally it. Inside shared.lua, you should have a bunch of fretta variables, which can either be found either in the base’s shared.lua or on this wiki page: http://maurits.tv/data/garrysmod/wiki/wiki.garrysmod.com/index9cef.html
The most important functions you’ll be wanting to use are GM:OnPreRoundStart, GM:OnRoundStart, GM:OnRoundEnd, etc. Basically, check out Prop Hunt for a good idea on how fretta gamemodes work.