Some games with attempts to boost 3rd party candidates that you can't actually play as
Here's a 1916 game. Wilson wins the entire Northeast except Maryland, but also loses everything else outside the South, as well as losing Tennessee to Hughes and Oklahoma to Benson, for a 263-258-10 electoral college deadlock (266 were needed to win). Of some note, the socialists go from winning 6% of the vote and 900k votes in 1912 to winning 9.3% of the vote and 1.7 million votes in this year, as well as winning a state
Here's a 1916 game that basically turns into a three-way split, with Hughes getting 191 EV and 33.7%, Wilson getting 187 EV and 37%, and Benson getting 28.4%
And here's a 1916 game where the socialists win, with 321 EV and 44.8% of the vote
Here's a 1916 game where the prohibition party wins 2 states and gets 18.2% of the vote
Here's a prohibition win
Also, here's a 1948 game where Truman wins but Wallace gets 4.7 million votes, 9.7%, and wins New York
And here's a 1948 game where Wallace gets 27% of the vote and wins 6 states
And here's a Wallace win