Lord Krsna appears at the end of the 28th Dwapar Yuga and then Lord Krsna again appears in the form of Sri Krsna Caitanya Mahāprabhu in the 28th Kaliyuga which is currently going on, kṛṣṇas tu bhagavān svayam. Otherwise in all other Kaliyuga, Gaur Narayana appears.
We are very fortunate to have received this human form of life after Srila Prabhupada, who founded ISKCON and fulfilled the mission of Caitanya Mahāprabhu by spreading the holy names across the world, as directed by Brahma to Nārada Muni.
Srila Prabhupada explained “Dharma or religion is the laws of the Lord”. It is explained by the guideline and these methods are to be used in each yuga to attain liberation.
Kaliyuga appears repeatedly in cycles, and each time it comes, the Lord has ordained that the only method to attain Him is through the chanting of the holy name.
Kaliyuga is extremely special. Kaliyuga in which Sri Krsna appears with Radharani as Caitanya Mahāprabhu happens once in one day of Brahma – śrī-kṛṣṇa-caitanya rādhā-kṛṣṇa nahe anya.
Śrīla Śukadeva Goswami explains that in Satya-yuga, we should meditate; in Treta yuga, perform sacrifices; in Dwapar yuga, serve the Lord’s lotus feet and in Kaliyuga, chant the holy names of the Lord.