Alternative investments tend to be offerings which are outside the big 4 assets, namely equities, fixed income, property and cash.
They are normally the ultimate "smoke and mirrors" product offering some kind of guarantee with a return linked to something no-one really understands. Or they offer things like "full equity participation with limited downside" or "superior risk-adjusted returns".
They prey on investor fears about stock-market losses, rather than explaining why investing in the great companies of the World has produced average returns of around 10% per annum over the last 100 years.
Do NOT be taken in by their sales blurb, maintain your discipline and continue to invest in human ingenuity by being an owner of some of the best companies in the World.