If Karma Yoga means with no desire for win or a lose, then what can be our ambition in doing a work? For example, what may be our ambition while playing a Game? Shall we play for a win? Kindly brief me what actually the core meaning of Karma Yoga is please?
The ambition will be to fulfill our 'dharma', our duties. A soldier dies in the battle, there is no gain for him, even if he is awarded a 'Param Vir Chakra' posthumously. He does it because it is his duty. That is what Gita says:
"sukha-duḥkhe same kṛitvā, lābhālābhau jayājayau'\;
tato yuddhāya yujyasva, naivaḿ pāpam avāpsyasi."
sukha — happiness; duḥkhe — and distress; same — in equanimity; kṛtvā — doing so; lābha-alābhau — both profit and loss; jaya-ajayau — both victory and defeat; tataḥ — thereafter; yuddhāya — for the sake of fighting; yujyasva — engage (fight); na — never; evam — in this way; pāpam — sinful reaction; avāpsyasi — you will gain.
Do thou fight for the sake of fighting, without considering happiness or distress, loss or gain, victory or defeat — and by so doing you shall never incur sin.
Many problems of the present times are because we have forgotten to work for our duty, our 'dharma'. Doing that is immensely satisfying, only that people do not try it these days. With best regards,