I offered a draw and regret it very much

I offered a draw and checked the computer analysis to find out that I only needed few more moves for a forced checkmate!

I even took a long time before offering a draw to see any checkmate sequence and failed to find it

http://ja.lichess.org/Vk5dXW0V/white
might be a good tactic puzzle

oops I thought I posted under game analysis
Sorry!

Tough break. Lesson learned.

I never offered a draw in my life

Nice combination.