At the beginning of his career, Maran was very interested in modern art trends. The first abstract paintings were completed in 1957-59. In the 1960s, Maran experimented with several trends in modern art, trying to bring the art experience contained in them to Estonian art as well. In addition to oil painting, he used gouache, tempera, pastel, collage. As one of the leaders of the avant-garde of Estonian art, he gave lectures and published articles on the applications of modern art.
In exhibitions Maran mostly displayed cityscapes and still lives with a simplified treatment of form.
The year 1968 was a turning point, when the artist's worldview turned towards religiosity. Since then he has painted nature-loving poetic pictures of the nature of Northern Estonia, flowers, preferably amaryllis, lilies and peonies, especially white ones, and old-fashioned still lives. Inspiringly expressing his clarified sense of life, Maran treats the nature and simple everyday objects with piety, which acquires inner harmony and a deeper ethical meaning.