Tolkappiyam sorts every Tamil word into four kinds: iyarchol (இயற்சொல்), the ordinary native word; thirichol (திரிசொல்), the poetic or altered word; thisaichol (திசைச்சொல்), the word from a neighbouring region; and vadasol (வடசொல்), the word from the north — from Sanskrit.
Ten words come up at a time, five rounds, and no word twice in a session. Click only the ones that came from Sanskrit, then check. Borrowing into Tamil is old but very uneven — thick in religion, philosophy and courtly life, thin in farming, kinship and the landscape — and the rounds draw across all of it, so the pattern shows itself as you play.