Important note: The Reichstag was elected by universal male suffrage for men over 25 (although there were some exceptions) on the basis of one man, one vote, although constituencies remained unchanged despite population shift, resulting in over-representation of rural areas. However, it is important to note that, despite the Reichstag's nominal power, parties focused mostly on overseeing the government, not trying to take power or develop a parliamentary form of government.
This map does not depict the results by constituency (a map of which can be found here), but rather by the governmental districts (Regierungsbezirke) present in many of the states that comprised the German Empire. However, I do hope to make a results by constituency map in the future.
In 1912, voters in Imperial Germany went to the polls to elect members of the Reichstag. However, unlike prior elections where the Social Democrats (SPD) received a plurality of votes but not seats, the SPD managed to secure 110 seats, more than doubling their members and becoming the largest group in the Reichstag. They did best in Berlin, Saxony, and the rest of central Germany, expanding their support significantly beyond their urban, working class base. Meanwhile, the Centre was delegated to the 2nd largest group in the Reichstag for the first time in 25 years, not even garnering half the number of votes as the SPD, but largely maintained their strength in the Rhineland and Bavaria, while Liberal parties saw further decline as their influence continued to fade. However, the biggest losses came from the Conservative camp, with the two largest conservative parties (the DKP & DRP) suffering a combined 28-seat loss. Notably, Conservatives saw a significant erosion of support in Prussia, particularly around Berlin.
Following the election, the SPD did become more vocal in parliament, particularly during the Zabern Affair where they demanded the resignation of Chancellor Theobald von Bethman Hollweg. However, these actions also demonstrated the limits of the SPD's, and by extension the Reichstag's, power, as the Kaiser (who had sole power to appoint Chancellors) simply ignored them and an attempt by the SPD to reject the Chancellor's budget failed, garnering only the support of the Polish Party. Unfortunately*, these elections would prove to be the last in the German Empire, as the First World War broke out only two years later, which Germany's defeat in lead to the dissolution of the German Empire and the establishment of the infamous Weimar Republic.
*I think it is unfortunate in the sense that the German Empire had a unique government structure, being a Frankenstein of traditional monarchy and parliamentary democracy, and it would have been interesting to see what happened had the SPD or other factions gotten enough power/interest to try and seriously assert themselves. However, I do not think it is unfortunate that a genocidal and expansionist monarchy no longer rules the largest country in Central Europe.