Seriously? I mean, surely you play Rocket League in HD with no problems. Right?
I found a good RetroAddicts clip to demonstrate how the retro stuff can look along with the bot reacting to Chris donating to the channel from his other main account. With most retro games being 4:3, there is plenty of space left over to setup the bot to display chat, recent events and live alerts:
clips.twitch.tv/PolishedTangibleLEDAMPEnergyCherry
You can easily do similar bot work on 16:9 games, too. Most streamers who do that will have the bot stuff over the game somewhere around the edges of the screen. Alternatively, although it's less common, it's also be possible to shrink the 16:9 game display a bit in OBS to leave a bit room for bot stuff and not cover any part of the game.
These are just a couple of bonus clips for laughs:
1. Chris and I playing Shadow Force. Mostly a co-op beat 'em up, but every now and then you get to fight each other.
clips.twitch.tv/GleamingUgliestYamFunRun
2. Steve and I playing the first bonus round in Street Fighter II CE. Steve is Honda. There's no way I could win as Bison, so I thought, "What the hell!"
clips.twitch.tv/AliveTenuousPonyNerfRedBlaster