In many ways, Dick's book is different, as you can see from the cover it envisages the USA lost the Second World War and was divided by Nazi Germany and Japan. This is the only map I have seen of the set-up though I think it is a bit wrong as in the novel the Germans stay East of the River Mississippi and so not holding Minnesota, Iowa, Missouri, Arkansas and Louisiana as shown here. If I remember correctly the Japanese have not gone much farther East than Nevada and Idaho; a series of collaborationist American states are mentioned as running the region of the Rockies.
Dick was a prolific author having 44 novels published in his lifetime (1928-82) and numerous short stories; other things were published after his death. I think he is the science fiction author who has had more of his stories turned into movies than any other; 'Blade Runner' (1982), 'Total Recall' (1990), 'Screamers' (1995), 'Minority Report' (2002), 'Imposter' (2002), 'Paycheck' (2003), 'A Scanner Darkly' (2006), 'Next' (2007) and 'Confessions d'un Barjo' are all adapted from his stories. Ironically I had always assumed 'Eternal Sunshine of the Spotless Mind' (2004) was based on a Dick novel; it certainly has many elements he enjoyed playing with.
Dick's novels, whilst predominantly science fiction, are often influenced by drug issues and mysticism. This applies to 'The Man in the High Castle' which is probably the novel which saw the best crossover into mainstream popular fiction before the 1980s. Towards the end of the book, through the use of the I-Ching method of predicting the future, many of the characters find they are in the 'wrong' world and that our world where Germany and Japan were defeated is the 'real' one. This undermines much of the basis of counter-factual fiction, but plays to Dick's interest in our perceptions and how these can be distorted, a theme which you will see even in the movie adaptations, such as Rick Deckard in 'Blade Runner' uncertain whether he is an android or now, the protagonists in 'Total Recall', 'Minority Report' and 'Paycheck' are all uncertain too what is the 'truth' and what has simply been fed to them. 'A Scanner Darkly' is about seeing the world through a drug haze.
I would argue, however, that Dick's denial of the possibility that a US defeat in the Second World War (which is unsurprising, if he had written anything different in 1961 he would never had had it published) fits an ongoing denial in the USA that they ever faced the danger of this or that they are not somehow the blessed nation. My political concerns about the USA creep in here, I fully acknowledge that, but I also think it is unhealthy for any country to think it is exempt from the dangers and possibilities of (violent) change that occur. This has often been a problem for the UK as well. The US inability to accept that it can be threatened and even be defeated is what has made it so difficult to cope with the Vietnam War, the 11th September attacks and the disintegration of the position in Iraq.
I found parallels with this in a computer game released by Talonsoft in the late 1990s. Their games in the so-called 'Campaign' series were produced from 1996 onwards. They seem pretty simple nowadays, being platoon-level turn based games with a landscape set out in hexagons like the board wargames that were popular in the 1980s. However, there were little animations and sound effects of the soldiers, tanks, etc. moving around. In addition there was immense historical detail of the battles they featured. They started with 'Eastern Front' which as it suggests featured battles of the Soviet campaign not only against the Germans but also the Finns, 1940-45. This was followed by 'West Front' which included North Africa as well as France, Belgium, the Netherlands and Germany and other locations of the Western Front of the Second World War. The final one was 'Rising Sun' which had a series of battles in the Pacific region. The games were produced as a boxed set with the three core games, plus all the upgrades as 'The World At War' in 2001. The company went on to do battles of the Arab-Israeli conflict too and it had already covered battles from the American Civil War.
Though the games seem simplistic now, the attention to detail and the ability to refight classic battles meant they were long a draw for wargamers. Naturally I enjoyed reversing history and was able to defeat the German attempt to take Crete in 1941 and stop the Panzers at the River Marne in 1940. As yet I have never been able to hold the bridge at Arnhem in 1944 for the Allies, but I kept a far larger bridgehead. In addition, upgrades of the games contained specifically counter-factual scenarios, such a series of battles around the German invasion of Britain in 1941. These allowed you to play either the German attackers or the British defenders not only in the South of England but even up to attacks on Manchester in the North-West.
I was interested to try out the Japanese invasion of the USA in 1942. Playing as Japanese characters especially in campaign mode which allows you to fight a sequence of connected battles was always difficult. Despite Talonsoft's efforts in terms of historical accuracy, whenever you played as a Japanese commander, even if you were not actually defeated, but failed to achieve all of the objectives you had been set, your character committed seppuku, even if only at the rank of major. Anyone who has looked at the Japanese campaign in China and the Pacific knows this did not happen. The Japanese were not always successful and their commanders only committed suicide when things seemed hopeless and they were holed up in some redoubt, not when they simply faced set-backs particularly on the advance. If the Imperial Japanese Army and Navy had adopted the ethics of Talonsoft, by 1942 there would have been no senior officers left.
What was more disconcerting is when you turn to the counter-factual invasions of the USA. In the 'West Front' game, you can play as the Germans and defeat the British so conquering the UK; equally you can play as the British fighting off the attacks. However, in the 'Rising Sun' game, you cannot play as the Japanese in attacking the USA, you can only play as the US defenders. In addition, in contrast to all of the other battles you can fight (which often turn quickly counter-factual even if starting off on a historical basis, otherwise what is the point of playing the computer wargame, you might as well simply watch a documentary), there is a statement saying how this never would have happened, that the Japanese never would have been able to invade the USA and so on. Is the USA that insecure about its place in the world that it cannot even let people play at invading it? Why is it alright for Talonsoft to let the UK fall to Nazism (and for Moscow, Leningrad and Stalingrad all to be overrun by German troops) but for the West coast of the USA for this not even to have been a possibility?
It is clear, as we have seen from looking at counter-factual books about the Second World War and even about the American Civil War there is still a lot of political currency in the USA around 'what if?' and that many Americans are unwilling to even countenance speculation over 'wrong' history whether in print or in a computer game. In my view this counts as a form of censorship as without speculation how can we truly test our society and the options it has faced and faces still. Without such testing it is all too easy to fall into seeing thing as simply 'inevitable' and 'right'.