The boost-to-win format in Sonic Forces results in shortened stages such as Mystic Jungle, Green Hill, and Prison Hall. The two-hour length of the game may feel excessive for casual players. The storytelling and execution in Sonic Forces are criticized for being inferior to even Sonic '06. The Avatar character is poorly received due to its generic nature. Tails' dialogue is deemed subpar, comparable to average Sonic fan-fiction, (to me, at least.)
Diving more in depth to the story, it's quite easy to tell that Forces had some great ideas, Dr. Robotnik nearly taking over the world 99 to 1, An actual self insert OC into the game, and Classic Sonic appearing, but the way it's implemented makes it so much worse. The Avatar is a nice addition, but with no gradual appearance. Take Tangle the Lemur, for example. In #3, she was first seen fending off the Egg-Robos, (or trying to.) It would give off a better flow in story.
The (99/1) plot was fine, not good, but not inherently bad at best, leaving it as okay here. Classic Sonic is only here to milk the nostalgia, no other reason. The controls for Classic Sonic are pretty much on par with Generations, leaving it to feel unpolished. Why reuse the same engine when you can look at the Hedgehog Engine and work upon it? This was the first mainline game in 5 YEARS, so you'd think they'd do it for a game released in the same year as Madden NFL 18, NBA 2K18, NBA Live 18, WWE 2K18, The Legend of Zelda: Breath of the Wild, Super Mario Odyssey, Persona 5, Divinity: Original Sin II and Horizon Zero Dawn, all great games in most gamers minds, but seeing this pit of a game along these doesn't feel right.
And the voice acting, is fine as well, but terrible in some moments. Take this cut-scene.
https://www.youtube.com/watch?v=pblUtUjpc_w
The fact that Roger is still acting for this one makes it feel so much worse, especially considering Lost World had better acting, surprisingly. The animation is good, not as good as.. say the Unleashed opening from 10 YEARS ago, and the animation is just normally fine. We had better animation in Rise Of Lyric. And Lost World. And Colours. (and nearly 4). And Unleashed. And I would go so far to say it's worse than 06's and Adventure 2's motion capture animation.
There are so much more problems with Forces, but I don't want to write an entire essay.