I flicked through some papers that described how one can obtain an ELO estimate based on a game. (Basically we were comparing players' moves to the best moves suggested by a strong chess engine. My question is, is there any online/offline resource when I can do this?
It's a matter of how much data there is. When you first get a rating in a tournament, it is a provisional rating until you reach X number of games. In the US I think you need 20 games. The provisional rating fluctuates more because of a single loss or win.
However, I recently obtained a copy of Houdini Pro 4. In the help contents is this: "Unix inventor and computer chess pioneer, Ken Thompson, has developed an algorithm which allows one to create an Elo rating list out of an arbitrary set of games".
There is also a step-wise process to generate an Elo list. So, perhaps it can not be done based "on a game", but maybe not too many more are needed using Ken's algorithm? Not sure, I never tried using that tool.
Jack Welbourne created a program like this called Chess Game Report.
Since about April 2023, chess.com's game review has an estimated rating feature. Unfortunately, unless you have a membership you only get one review a day. I can't vouch for its accuracy either.
Software based on a game, probably not to be honest, the best way to get your strength 'measured' is by playing on some internet chess server where you can obtain an online rating.
Although this website can give you elo rating estimate based on a series of exercises which you do. http://www.chessmaniac.com/ELORating/ELO_Chess_Rating.shtml
You are lucky, because I have just published an Android App that does exactly what you need. It is called "Analyze your games" and you can get it here for free: