The 36-year-old missed last Saturday's Premier League defeat of Swansea with an ankle problem, but was thrust into the starting line-up for Wednesday night's Champions League clash with Schalke.
Drogba was unable to add to his 157 Blues goals - accrued over eight years, from 2004 to 2012 - and Chelsea were punished as the Germans claimed a 1-1 draw.
"For a first game they were okay, kind of okay," Drogba, who left Stamford Bridge after scoring the decisive penalty in the 2012 European Cup win, told Chelsea TV.
Drogba twice was unable to convert what would once have been meat and drink to him, firstly when Willian crossed inside the six-yard box and then when Eden Hazard played him in.
Drogba added: "I had (chances), especially the one in the second half. It was a clear chance and I think it's unlucky. If I score there there's no more game. The fact that you don't score, they still believe in the equaliser and that's what happened afterwards."