Learn Icelandic: Hvílíkt sjónarspil!

It acts as a strong adjective and must agree in gender, number, and case with the noun it describes. Because sjónarspil is a neuter noun in the nominative singular, the determiner takes the strong neuter singular form hvílíkt.

Should I use the definite or indefinite form of the noun after hvílíkur?

You must use the indefinite form. Just like in English where we say 'what a spectacle' instead of 'what the spectacle', you use the indefinite sjónarspil rather than the definite sjónarspilið.

How is the compound noun sjónarspil constructed?

It is made of two words: sjónar, which is the genitive (possessive) singular form of sjón (sight or vision), and the neuter noun spil (play or game). Literally, it translates to 'a play of sight'.

If I wanted to exclaim about multiple events ('What spectacles!'), how would this sentence change?

The neuter noun sjónarspil happens to look exactly the same in the nominative plural, but the determiner must change to agree with it. The strong neuter plural form of the determiner is hvílík, so the exclamation would become Hvílík sjónarspil!