It is very difficult to understand Greece with North-West Europe references. Not that Greece is particularly "exotic" or "alien", but mostly because it has a rather troubled recent History that most foreigners or visiting tourists don't know well (and I was one of these poorly informed people). The political landscape in Greece used to be rather simple, at least seen from the outside, opposing since 1974 conservatives (Nea Democratia) to socialists (PASOK). Fringe smaller parties also existed, such as populist right wing LAOS (a Church and fatherland resurgence of older parties) or the older Communist KKE (pronounce koeh-koeh-A). But they never were in a position to challenge the duopoly of the two party system and the fact is that most current and numerous parties in Greece did not exist under their current form only 10 years ago.
Most of this is linked to the fact that Greece, from 1967 to 1974, was under the regime of conservative putschist colonels. Both conservative and socialist parties were created as a reaction to this regime and the communist KKE (which had been clandestine since the end of the Second World War) was only legalized at this time too. This has had a profound influence on the way Greek citizens view authority, political parties and ideologies. Parties were identified, consciously or not, in relation to their relationship with the colonels' junta (as it is called in Greece) and ideologies, behaviors, political myths and realities are also shaped by the trauma of the brutal dictature. Nationalist parties are often associated to this regime and illegal or damaging activities of leftist ones are often considered less negatively, because of their resistance to it.
All this changed in the last 10 to 5 years, and even more with the recent economic crisis. The political system has suddenly exploded, ending the dominance of the two party system. New players in the political field include radical left Syriza, Democratic Left (Aristera), Golden Dawn (neo-nazis), the ecologist Green and LAOS (Religious Nationalists). Most of these parties embody in fact, a certain modernity in the Greek system, for the better and for the worst. Indeed, all these new parties reflect issues and ideas that are found now in most other democracies, but which were prevented from expressing themselves by the two-party system. I use this term on purpose, as this "system" was not in any way a product of the Constitution of the IIIrd Hellenic Republic, but because it was, in my opinion a perversion of it. In other terms, both conservative and socialist put in place a strong nepotism and clientele system, corrupting the Greek democracy and effectively preventing the occurrence of political and ideological alternative. Of course, one should avoid excessive generalisation, and both parties certainly had honest members. But the leadership of these parties clearly and obviously maintained their power by way of services against votes and money against services. To get anything done in Greece (public or private) you would need a political support in one of these two parties. To a certain extent, this is still true today.
But the emergence and rise of other political and ideological offer, as well as the systematic failure by both traditional parties to handle the economic crisis, making it even worse, has created the current political quagmire. No party at the moment can claim any kind of majority. But more importantly, the separation between the parties no longer reflect the right or left paradigm but also the separation between old school politics and the new ways. The issue is as much generational as it is ideological. Hence the impossibility to build any coalition between parties which should, from an external point of view, be logical allies. It goes against the mentality of the politician involved but also against years of History. They are unable to handle the crisis or give coordinated answer to Greece's problems simply because there is no structure any more in Greece politics.