Prior to coming to Peterborough, Ontario, to play for the Peterborough Petes, Martschini was a successful player with many teams in Zug, playing in Top Mini, Elite Novizen, Elite Jr. A, and Top Junioren leagues with teams varying from under-15 to under-20.

[1] When he arrived in the OHL for the 2010–11 season, Martschini was a top player for the Petes, notching 20 goals and 38 assists for a total of 58 points in 61 games, just shy of a point-per-game.

Both were selected in the 2011 NHL Entry Draft, by the Ottawa Senators and Boston Bruins, respectively, but Martschini was passed over.

Prior to the 2015–16 season, Martschini agreed to a four-year contract extension with EV Zug worth CHF 2.5 million.

On 23 August 2019 Martschini was signed to an early three-year contract extension by Zug worth CHF 2.175 million through the 2022/23 season.