What a great branch! So many great posts. Ng Yi Shu in particular stands out for me, along with Jolene's point on the Government's role in 'guiding' Singaporean cultural growth.
From an outsider who has lived in & loves Singapore, the pillars of identity could be:
Speaking & understanding the beautiful contours of Singlish.
Food as identity and as interface with other races/cultures.
Absolutely hilarious & very relentless self-referential, self-deprecating humour (e.g. The 5 K's in link below).
A confusing relationship between identity & race, which can become xenophobia & racism toward recent immigrants. Old policy of 'Multi-Racialism' might be at fault.
Unclear expression of identity at home; identity seems to resolve overseas.