The 26-year-old, who had his contact terminated with the Lions at the start of the week, has criticised Millwall's style of football.
He told the Advertiser: "It was my first time at training (Wednesday) and it was something special. For me it was the first time I saw everyone playing and it was so nice. There were a lot of good players and the passing football is good.
"They play on the grass and that is football. We call it 'foot-ball' and they play football. The biggest teams in the world - Barcelona, Bayern Munich - they all play on the grass. They don't play in the air.
"It's football. When you've got the ball you have to chase and if you don't chase you get booed that's not good. I think at Millwall, I feel it was more about long ball and chasing the ball. When I saw it at Swindon it was nice football and I am excited."
N'Guessan had made just one substitute appearance for Millwall this season.