Under the constitutional division of powers in India, a state government can legislate only over 'gambling games'. Unfortunately, gambling is not defined in the constitution, nor can the central government define it through a law as that would mean encroaching on state government's powers.
So now the onus falls on the state governments to define gambling appropriately without violating constitutional division of powers.
The Tamil Nadu ("TN") state law banning online gambling ends up outlawing, inter alia, any online game involving pre-dominance of skills if the skill required to beat chance is 'superlative'.
As a result of such definition in the TN state law, it is possible to argue that such a definition is unconstitutional because to call a skill-based game having an element of chance, as gambling if superlative skill is needed, would be letting a state government encroach upon non-gambling games for which the state government is not constitutionally empowered.
However, if the Hon'ble Supreme Court ("SC") were to accept the definition used in TN State law, as the expanded definition of 'gambling', then things would remain kosher. Presently, the TN State law is challenged at the High Court of Madras, but if it fails at that stage, it is expected that the same may come up for consideration before the SC, which should eventually provide a finality to the matter.
Alternatively, the central government could consider regulating skill based games that require superlative skills to beat elements of chance - however, that won't be without issues of definitions as 'superlative' is quite a subjective criteria.
