When starting a game by yourself, even in “offline” mode, cheats don’t work. They only seem to work if you run a map from the world editor or play the campaign.
Also, again, when playing a game by yourself, even in “offline” mode, opening the Menu (F10) does not pause the game. This previously paused the game in the classic client. In Reforged, you are limited to 3 pauses as if it was a multiplayer match.
During campaign, however, going to the in-game menu (F10) does pause the game.